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reveal.js
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reveal.js
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			/*!
			* reveal.js
			* http://lab.hakim.se/reveal-js
			* MIT licensed
			*
			* Copyright (C) 2017 Hakim El Hattab, http://hakim.se
			*/
			(function( root, factory ) {
			if( typeof define === 'function' && define.amd ) {
			// AMD. Register as an anonymous module.
			define( function() {
			root.Reveal = factory();
			return root.Reveal;
			} );
			} else if( typeof exports === 'object' ) {
			// Node. Does not work with strict CommonJS.
			module.exports = factory();
			} else {
			// Browser globals.
			root.Reveal = factory();
			}
			}( this, function() {

			'use strict';

			var Reveal;

			// The reveal.js version
			var VERSION = '3.5.0';

			var SLIDES_SELECTOR = '.slides section',
			HORIZONTAL_SLIDES_SELECTOR = '.slides>section',
			VERTICAL_SLIDES_SELECTOR = '.slides>section.present>section',
			HOME_SLIDE_SELECTOR = '.slides>section:first-of-type',
			UA = navigator.userAgent,

			// Configuration defaults, can be overridden at initialization time
			config = {

			// The "normal" size of the presentation, aspect ratio will be preserved
			// when the presentation is scaled to fit different resolutions
			width: 960,
			height: 700,

			// Factor of the display size that should remain empty around the content
			margin: 0.04,

			// Bounds for smallest/largest possible scale to apply to content
			minScale: 0.2,
			maxScale: 2.0,

			// Display controls in the bottom right corner
			controls: true,

			// Display a presentation progress bar
			progress: true,

			// Display the page number of the current slide
			slideNumber: false,

			// Determine which displays to show the slide number on
			showSlideNumber: 'all',

			// Push each slide change to the browser history
			history: false,

			// Enable keyboard shortcuts for navigation
			keyboard: true,

			// Optional function that blocks keyboard events when retuning false
			keyboardCondition: null,

			// Enable the slide overview mode
			overview: true,

			// Vertical centering of slides
			center: true,

			// Enables touch navigation on devices with touch input
			touch: true,

			// Loop the presentation
			loop: false,

			// Change the presentation direction to be RTL
			rtl: false,

			// Randomizes the order of slides each time the presentation loads
			shuffle: false,

			// Turns fragments on and off globally
			fragments: true,

			// Flags if the presentation is running in an embedded mode,
			// i.e. contained within a limited portion of the screen
			embedded: false,

			// Flags if we should show a help overlay when the question-mark
			// key is pressed
			help: true,

			// Flags if it should be possible to pause the presentation (blackout)
			pause: true,

			// Flags if speaker notes should be visible to all viewers
			showNotes: false,

			// Global override for autolaying embedded media (video/audio/iframe)
			// - null: Media will only autoplay if data-autoplay is present
			// - true: All media will autoplay, regardless of individual setting
			// - false: No media will autoplay, regardless of individual setting
			autoPlayMedia: null,

			// Number of milliseconds between automatically proceeding to the
			// next slide, disabled when set to 0, this value can be overwritten
			// by using a data-autoslide attribute on your slides
			autoSlide: 0,

			// Stop auto-sliding after user input
			autoSlideStoppable: true,

			// Use this method for navigation when auto-sliding (defaults to navigateNext)
			autoSlideMethod: null,

			// Enable slide navigation via mouse wheel
			mouseWheel: false,

			// Apply a 3D roll to links on hover
			rollingLinks: false,

			// Hides the address bar on mobile devices
			hideAddressBar: true,

			// Opens links in an iframe preview overlay
			previewLinks: false,

			// Exposes the reveal.js API through window.postMessage
			postMessage: true,

			// Dispatches all reveal.js events to the parent window through postMessage
			postMessageEvents: false,

			// Focuses body when page changes visibility to ensure keyboard shortcuts work
			focusBodyOnPageVisibilityChange: true,

			// Transition style
			transition: 'slide', // none/fade/slide/convex/concave/zoom

			// Transition speed
			transitionSpeed: 'default', // default/fast/slow

			// Transition style for full page slide backgrounds
			backgroundTransition: 'fade', // none/fade/slide/convex/concave/zoom

			// Parallax background image
			parallaxBackgroundImage: '', // CSS syntax, e.g. "a.jpg"

			// Parallax background size
			parallaxBackgroundSize: '', // CSS syntax, e.g. "3000px 2000px"

			// Amount of pixels to move the parallax background per slide step
			parallaxBackgroundHorizontal: null,
			parallaxBackgroundVertical: null,

			// The maximum number of pages a single slide can expand onto when printing
			// to PDF, unlimited by default
			pdfMaxPagesPerSlide: Number.POSITIVE_INFINITY,

			// Offset used to reduce the height of content within exported PDF pages.
			// This exists to account for environment differences based on how you
			// print to PDF. CLI printing options, like phantomjs and wkpdf, can end
			// on precisely the total height of the document whereas in-browser
			// printing has to end one pixel before.
			pdfPageHeightOffset: -1,

			// Number of slides away from the current that are visible
			viewDistance: 3,

			// The display mode that will be used to show slides
			display: 'block',

			// Script dependencies to load
			dependencies: []

			},

			// Flags if Reveal.initialize() has been called
			initialized = false,

			// Flags if reveal.js is loaded (has dispatched the 'ready' event)
			loaded = false,

			// Flags if the overview mode is currently active
			overview = false,

			// Holds the dimensions of our overview slides, including margins
			overviewSlideWidth = null,
			overviewSlideHeight = null,

			// The horizontal and vertical index of the currently active slide
			indexh,
			indexv,

			// The previous and current slide HTML elements
			previousSlide,
			currentSlide,

			previousBackground,

			// Slides may hold a data-state attribute which we pick up and apply
			// as a class to the body. This list contains the combined state of
			// all current slides.
			state = [],

			// The current scale of the presentation (see width/height config)
			scale = 1,

			// CSS transform that is currently applied to the slides container,
			// split into two groups
			slidesTransform = { layout: '', overview: '' },

			// Cached references to DOM elements
			dom = {},

			// Features supported by the browser, see #checkCapabilities()
			features = {},

			// Client is a mobile device, see #checkCapabilities()
			isMobileDevice,

			// Client is a desktop Chrome, see #checkCapabilities()
			isChrome,

			// Throttles mouse wheel navigation
			lastMouseWheelStep = 0,

			// Delays updates to the URL due to a Chrome thumbnailer bug
			writeURLTimeout = 0,

			// Flags if the interaction event listeners are bound
			eventsAreBound = false,

			// The current auto-slide duration
			autoSlide = 0,

			// Auto slide properties
			autoSlidePlayer,
			autoSlideTimeout = 0,
			autoSlideStartTime = -1,
			autoSlidePaused = false,

			// Holds information about the currently ongoing touch input
			touch = {
			startX: 0,
			startY: 0,
			startSpan: 0,
			startCount: 0,
			captured: false,
			threshold: 40
			},

			// Holds information about the keyboard shortcuts
			keyboardShortcuts = {
			'N , SPACE': 'Next slide',
			'P': 'Previous slide',
			'← , H': 'Navigate left',
			'→ , L': 'Navigate right',
			'↑ , K': 'Navigate up',
			'↓ , J': 'Navigate down',
			'Home': 'First slide',
			'End': 'Last slide',
			'B , .': 'Pause',
			'F': 'Fullscreen',
			'ESC, O': 'Slide overview'
			};

			/**
			* Starts up the presentation if the client is capable.
			*/
			function initialize( options ) {

			// Make sure we only initialize once
			if( initialized === true ) return;

			initialized = true;

			checkCapabilities();

			if( !features.transforms2d && !features.transforms3d ) {
			document.body.setAttribute( 'class', 'no-transforms' );

			// Since JS won't be running any further, we load all lazy
			// loading elements upfront
			var images = toArray( document.getElementsByTagName( 'img' ) ),
			iframes = toArray( document.getElementsByTagName( 'iframe' ) );

			var lazyLoadable = images.concat( iframes );

			for( var i = 0, len = lazyLoadable.length; i < len; i++ ) {
			var element = lazyLoadable[i];
			if( element.getAttribute( 'data-src' ) ) {
			element.setAttribute( 'src', element.getAttribute( 'data-src' ) );
			element.removeAttribute( 'data-src' );
			}
			}

			// If the browser doesn't support core features we won't be
			// using JavaScript to control the presentation
			return;
			}

			// Cache references to key DOM elements
			dom.wrapper = document.querySelector( '.reveal' );
			dom.slides = document.querySelector( '.reveal .slides' );

			// Force a layout when the whole page, incl fonts, has loaded
			window.addEventListener( 'load', layout, false );

			var query = Reveal.getQueryHash();

			// Do not accept new dependencies via query config to avoid
			// the potential of malicious script injection
			if( typeof query['dependencies'] !== 'undefined' ) delete query['dependencies'];

			// Copy options over to our config object
			extend( config, options );
			extend( config, query );

			// Hide the address bar in mobile browsers
			hideAddressBar();

			// Loads the dependencies and continues to #start() once done
			load();

			}

			/**
			* Inspect the client to see what it's capable of, this
			* should only happens once per runtime.
			*/
			function checkCapabilities() {

			isMobileDevice = /(iphone\|ipod\|ipad\|android)/gi.test( UA );
			isChrome = /chrome/i.test( UA ) && !/edge/i.test( UA );

			var testElement = document.createElement( 'div' );

			features.transforms3d = 'WebkitPerspective' in testElement.style \|\|
			'MozPerspective' in testElement.style \|\|
			'msPerspective' in testElement.style \|\|
			'OPerspective' in testElement.style \|\|
			'perspective' in testElement.style;

			features.transforms2d = 'WebkitTransform' in testElement.style \|\|
			'MozTransform' in testElement.style \|\|
			'msTransform' in testElement.style \|\|
			'OTransform' in testElement.style \|\|
			'transform' in testElement.style;

			features.requestAnimationFrameMethod = window.requestAnimationFrame \|\| window.webkitRequestAnimationFrame \|\| window.mozRequestAnimationFrame;
			features.requestAnimationFrame = typeof features.requestAnimationFrameMethod === 'function';

			features.canvas = !!document.createElement( 'canvas' ).getContext;

			// Transitions in the overview are disabled in desktop and
			// Safari due to lag
			features.overviewTransitions = !/Version\/[\d\.]+.*Safari/.test( UA );

			// Flags if we should use zoom instead of transform to scale
			// up slides. Zoom produces crisper results but has a lot of
			// xbrowser quirks so we only use it in whitelsited browsers.
			features.zoom = 'zoom' in testElement.style && !isMobileDevice &&
			( isChrome \|\| /Version\/[\d\.]+.*Safari/.test( UA ) );

			}

			/**
			* Loads the dependencies of reveal.js. Dependencies are
			* defined via the configuration option 'dependencies'
			* and will be loaded prior to starting/binding reveal.js.
			* Some dependencies may have an 'async' flag, if so they
			* will load after reveal.js has been started up.
			*/
			function load() {

			var scripts = [],
			scriptsAsync = [],
			scriptsToPreload = 0;

			// Called once synchronous scripts finish loading
			function proceed() {
			if( scriptsAsync.length ) {
			// Load asynchronous scripts
			head.js.apply( null, scriptsAsync );
			}

			start();
			}

			function loadScript( s ) {
			head.ready( s.src.match( /([\w\d_\-])\.?js$\|[^\\\/]$/i )[0], function() {
			// Extension may contain callback functions
			if( typeof s.callback === 'function' ) {
			s.callback.apply( this );
			}

			if( --scriptsToPreload === 0 ) {
			proceed();
			}
			});
			}

			for( var i = 0, len = config.dependencies.length; i < len; i++ ) {
			var s = config.dependencies[i];

			// Load if there's no condition or the condition is truthy
			if( !s.condition \|\| s.condition() ) {
			if( s.async ) {
			scriptsAsync.push( s.src );
			}
			else {
			scripts.push( s.src );
			}

			loadScript( s );
			}
			}

			if( scripts.length ) {
			scriptsToPreload = scripts.length;

			// Load synchronous scripts
			head.js.apply( null, scripts );
			}
			else {
			proceed();
			}

			}

			/**
			* Starts up reveal.js by binding input events and navigating
			* to the current URL deeplink if there is one.
			*/
			function start() {

			// Make sure we've got all the DOM elements we need
			setupDOM();

			// Listen to messages posted to this window
			setupPostMessage();

			// Prevent the slides from being scrolled out of view
			setupScrollPrevention();

			// Resets all vertical slides so that only the first is visible
			resetVerticalSlides();

			// Updates the presentation to match the current configuration values
			configure();

			// Read the initial hash
			readURL();

			// Update all backgrounds
			updateBackground( true );

			// Notify listeners that the presentation is ready but use a 1ms
			// timeout to ensure it's not fired synchronously after #initialize()
			setTimeout( function() {
			// Enable transitions now that we're loaded
			dom.slides.classList.remove( 'no-transition' );

			loaded = true;

			dom.wrapper.classList.add( 'ready' );

			dispatchEvent( 'ready', {
			'indexh': indexh,
			'indexv': indexv,
			'currentSlide': currentSlide
			} );
			}, 1 );

			// Special setup and config is required when printing to PDF
			if( isPrintingPDF() ) {
			removeEventListeners();

			// The document needs to have loaded for the PDF layout
			// measurements to be accurate
			if( document.readyState === 'complete' ) {
			setupPDF();
			}
			else {
			window.addEventListener( 'load', setupPDF );
			}
			}

			}

			/**
			* Finds and stores references to DOM elements which are
			* required by the presentation. If a required element is
			* not found, it is created.
			*/
			function setupDOM() {

			// Prevent transitions while we're loading
			dom.slides.classList.add( 'no-transition' );

			// Background element
			dom.background = createSingletonNode( dom.wrapper, 'div', 'backgrounds', null );

			// Progress bar
			dom.progress = createSingletonNode( dom.wrapper, 'div', 'progress', '<span></span>' );
			dom.progressbar = dom.progress.querySelector( 'span' );

			// Arrow controls
			createSingletonNode( dom.wrapper, 'aside', 'controls',
			'<button class="navigate-left" aria-label="previous slide"></button>' +
			'<button class="navigate-right" aria-label="next slide"></button>' +
			'<button class="navigate-up" aria-label="above slide"></button>' +
			'<button class="navigate-down" aria-label="below slide"></button>' );

			// Slide number
			dom.slideNumber = createSingletonNode( dom.wrapper, 'div', 'slide-number', '' );

			// Element containing notes that are visible to the audience
			dom.speakerNotes = createSingletonNode( dom.wrapper, 'div', 'speaker-notes', null );
			dom.speakerNotes.setAttribute( 'data-prevent-swipe', '' );
			dom.speakerNotes.setAttribute( 'tabindex', '0' );

			// Overlay graphic which is displayed during the paused mode
			createSingletonNode( dom.wrapper, 'div', 'pause-overlay', null );

			// Cache references to elements
			dom.controls = document.querySelector( '.reveal .controls' );

			dom.wrapper.setAttribute( 'role', 'application' );

			// There can be multiple instances of controls throughout the page
			dom.controlsLeft = toArray( document.querySelectorAll( '.navigate-left' ) );
			dom.controlsRight = toArray( document.querySelectorAll( '.navigate-right' ) );
			dom.controlsUp = toArray( document.querySelectorAll( '.navigate-up' ) );
			dom.controlsDown = toArray( document.querySelectorAll( '.navigate-down' ) );
			dom.controlsPrev = toArray( document.querySelectorAll( '.navigate-prev' ) );
			dom.controlsNext = toArray( document.querySelectorAll( '.navigate-next' ) );

			dom.statusDiv = createStatusDiv();
			}

			/**
			* Creates a hidden div with role aria-live to announce the
			* current slide content. Hide the div off-screen to make it
			* available only to Assistive Technologies.
			*
			* @return {HTMLElement}
			*/
			function createStatusDiv() {

			var statusDiv = document.getElementById( 'aria-status-div' );
			if( !statusDiv ) {
			statusDiv = document.createElement( 'div' );
			statusDiv.style.position = 'absolute';
			statusDiv.style.height = '1px';
			statusDiv.style.width = '1px';
			statusDiv.style.overflow = 'hidden';
			statusDiv.style.clip = 'rect( 1px, 1px, 1px, 1px )';
			statusDiv.setAttribute( 'id', 'aria-status-div' );
			statusDiv.setAttribute( 'aria-live', 'polite' );
			statusDiv.setAttribute( 'aria-atomic','true' );
			dom.wrapper.appendChild( statusDiv );
			}
			return statusDiv;

			}

			/**
			* Converts the given HTML element into a string of text
			* that can be announced to a screen reader. Hidden
			* elements are excluded.
			*/
			function getStatusText( node ) {

			var text = '';

			// Text node
			if( node.nodeType === 3 ) {
			text += node.textContent;
			}
			// Element node
			else if( node.nodeType === 1 ) {

			var isAriaHidden = node.getAttribute( 'aria-hidden' );
			var isDisplayHidden = window.getComputedStyle( node )['display'] === 'none';
			if( isAriaHidden !== 'true' && !isDisplayHidden ) {

			toArray( node.childNodes ).forEach( function( child ) {
			text += getStatusText( child );
			} );

			}

			}

			return text;

			}

			/**
			* Configures the presentation for printing to a static
			* PDF.
			*/
			function setupPDF() {

			var slideSize = getComputedSlideSize( window.innerWidth, window.innerHeight );

			// Dimensions of the PDF pages
			var pageWidth = Math.floor( slideSize.width * ( 1 + config.margin ) ),
			pageHeight = Math.floor( slideSize.height * ( 1 + config.margin ) );

			// Dimensions of slides within the pages
			var slideWidth = slideSize.width,
			slideHeight = slideSize.height;

			// Let the browser know what page size we want to print
			injectStyleSheet( '@page{size:'+ pageWidth +'px '+ pageHeight +'px; margin: 0px;}' );

			// Limit the size of certain elements to the dimensions of the slide
			injectStyleSheet( '.reveal section>img, .reveal section>video, .reveal section>iframe{max-width: '+ slideWidth +'px; max-height:'+ slideHeight +'px}' );

			document.body.classList.add( 'print-pdf' );
			document.body.style.width = pageWidth + 'px';
			document.body.style.height = pageHeight + 'px';

			// Make sure stretch elements fit on slide
			layoutSlideContents( slideWidth, slideHeight );

			// Add each slide's index as attributes on itself, we need these
			// indices to generate slide numbers below
			toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( hslide, h ) {
			hslide.setAttribute( 'data-index-h', h );

			if( hslide.classList.contains( 'stack' ) ) {
			toArray( hslide.querySelectorAll( 'section' ) ).forEach( function( vslide, v ) {
			vslide.setAttribute( 'data-index-h', h );
			vslide.setAttribute( 'data-index-v', v );
			} );
			}
			} );

			// Slide and slide background layout
			toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) ).forEach( function( slide ) {

			// Vertical stacks are not centred since their section
			// children will be
			if( slide.classList.contains( 'stack' ) === false ) {
			// Center the slide inside of the page, giving the slide some margin
			var left = ( pageWidth - slideWidth ) / 2,
			top = ( pageHeight - slideHeight ) / 2;

			var contentHeight = slide.scrollHeight;
			var numberOfPages = Math.max( Math.ceil( contentHeight / pageHeight ), 1 );

			// Adhere to configured pages per slide limit
			numberOfPages = Math.min( numberOfPages, config.pdfMaxPagesPerSlide );

			// Center slides vertically
			if( numberOfPages === 1 && config.center \|\| slide.classList.contains( 'center' ) ) {
			top = Math.max( ( pageHeight - contentHeight ) / 2, 0 );
			}

			// Wrap the slide in a page element and hide its overflow
			// so that no page ever flows onto another
			var page = document.createElement( 'div' );
			page.className = 'pdf-page';
			page.style.height = ( ( pageHeight + config.pdfPageHeightOffset ) * numberOfPages ) + 'px';
			slide.parentNode.insertBefore( page, slide );
			page.appendChild( slide );

			// Position the slide inside of the page
			slide.style.left = left + 'px';
			slide.style.top = top + 'px';
			slide.style.width = slideWidth + 'px';

			if( slide.slideBackgroundElement ) {
			page.insertBefore( slide.slideBackgroundElement, slide );
			}

			// Inject notes if `showNotes` is enabled
			if( config.showNotes ) {

			// Are there notes for this slide?
			var notes = getSlideNotes( slide );
			if( notes ) {

			var notesSpacing = 8;
			var notesLayout = typeof config.showNotes === 'string' ? config.showNotes : 'inline';
			var notesElement = document.createElement( 'div' );
			notesElement.classList.add( 'speaker-notes' );
			notesElement.classList.add( 'speaker-notes-pdf' );
			notesElement.setAttribute( 'data-layout', notesLayout );
			notesElement.innerHTML = notes;

			if( notesLayout === 'separate-page' ) {
			page.parentNode.insertBefore( notesElement, page.nextSibling );
			}
			else {
			notesElement.style.left = notesSpacing + 'px';
			notesElement.style.bottom = notesSpacing + 'px';
			notesElement.style.width = ( pageWidth - notesSpacing*2 ) + 'px';
			page.appendChild( notesElement );
			}

			}

			}

			// Inject slide numbers if `slideNumbers` are enabled
			if( config.slideNumber && /all\|print/i.test( config.showSlideNumber ) ) {
			var slideNumberH = parseInt( slide.getAttribute( 'data-index-h' ), 10 ) + 1,
			slideNumberV = parseInt( slide.getAttribute( 'data-index-v' ), 10 ) + 1;

			var numberElement = document.createElement( 'div' );
			numberElement.classList.add( 'slide-number' );
			numberElement.classList.add( 'slide-number-pdf' );
			numberElement.innerHTML = formatSlideNumber( slideNumberH, '.', slideNumberV );
			page.appendChild( numberElement );
			}
			}

			} );

			// Show all fragments
			toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ' .fragment' ) ).forEach( function( fragment ) {
			fragment.classList.add( 'visible' );
			} );

			// Notify subscribers that the PDF layout is good to go
			dispatchEvent( 'pdf-ready' );

			}

			/**
			* This is an unfortunate necessity. Some actions – such as
			* an input field being focused in an iframe or using the
			* keyboard to expand text selection beyond the bounds of
			* a slide – can trigger our content to be pushed out of view.
			* This scrolling can not be prevented by hiding overflow in
			* CSS (we already do) so we have to resort to repeatedly
			* checking if the slides have been offset :(
			*/
			function setupScrollPrevention() {

			setInterval( function() {
			if( dom.wrapper.scrollTop !== 0 \|\| dom.wrapper.scrollLeft !== 0 ) {
			dom.wrapper.scrollTop = 0;
			dom.wrapper.scrollLeft = 0;
			}
			}, 1000 );

			}

			/**
			* Creates an HTML element and returns a reference to it.
			* If the element already exists the existing instance will
			* be returned.
			*
			* @param {HTMLElement} container
			* @param {string} tagname
			* @param {string} classname
			* @param {string} innerHTML
			*
			* @return {HTMLElement}
			*/
			function createSingletonNode( container, tagname, classname, innerHTML ) {

			// Find all nodes matching the description
			var nodes = container.querySelectorAll( '.' + classname );

			// Check all matches to find one which is a direct child of
			// the specified container
			for( var i = 0; i < nodes.length; i++ ) {
			var testNode = nodes[i];
			if( testNode.parentNode === container ) {
			return testNode;
			}
			}

			// If no node was found, create it now
			var node = document.createElement( tagname );
			node.classList.add( classname );
			if( typeof innerHTML === 'string' ) {
			node.innerHTML = innerHTML;
			}
			container.appendChild( node );

			return node;

			}

			/**
			* Creates the slide background elements and appends them
			* to the background container. One element is created per
			* slide no matter if the given slide has visible background.
			*/
			function createBackgrounds() {

			var printMode = isPrintingPDF();

			// Clear prior backgrounds
			dom.background.innerHTML = '';
			dom.background.classList.add( 'no-transition' );

			// Iterate over all horizontal slides
			toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( slideh ) {

			var backgroundStack = createBackground( slideh, dom.background );

			// Iterate over all vertical slides
			toArray( slideh.querySelectorAll( 'section' ) ).forEach( function( slidev ) {

			createBackground( slidev, backgroundStack );

			backgroundStack.classList.add( 'stack' );

			} );

			} );

			// Add parallax background if specified
			if( config.parallaxBackgroundImage ) {

			dom.background.style.backgroundImage = 'url("' + config.parallaxBackgroundImage + '")';
			dom.background.style.backgroundSize = config.parallaxBackgroundSize;

			// Make sure the below properties are set on the element - these properties are
			// needed for proper transitions to be set on the element via CSS. To remove
			// annoying background slide-in effect when the presentation starts, apply
			// these properties after short time delay
			setTimeout( function() {
			dom.wrapper.classList.add( 'has-parallax-background' );
			}, 1 );

			}
			else {

			dom.background.style.backgroundImage = '';
			dom.wrapper.classList.remove( 'has-parallax-background' );

			}

			}

			/**
			* Creates a background for the given slide.
			*
			* @param {HTMLElement} slide
			* @param {HTMLElement} container The element that the background
			* should be appended to
			* @return {HTMLElement} New background div
			*/
			function createBackground( slide, container ) {

			var data = {
			background: slide.getAttribute( 'data-background' ),
			backgroundSize: slide.getAttribute( 'data-background-size' ),
			backgroundImage: slide.getAttribute( 'data-background-image' ),
			backgroundVideo: slide.getAttribute( 'data-background-video' ),
			backgroundIframe: slide.getAttribute( 'data-background-iframe' ),
			backgroundColor: slide.getAttribute( 'data-background-color' ),
			backgroundRepeat: slide.getAttribute( 'data-background-repeat' ),
			backgroundPosition: slide.getAttribute( 'data-background-position' ),
			backgroundTransition: slide.getAttribute( 'data-background-transition' )
			};

			var element = document.createElement( 'div' );

			// Carry over custom classes from the slide to the background
			element.className = 'slide-background ' + slide.className.replace( /present\|past\|future/, '' );

			if( data.background ) {
			// Auto-wrap image urls in url(...)
			if( /^(http\|file\|\/\/)/gi.test( data.background ) \|\| /\.(svg\|png\|jpg\|jpeg\|gif\|bmp)([?#]\|$)/gi.test( data.background ) ) {
			slide.setAttribute( 'data-background-image', data.background );
			}
			else {
			element.style.background = data.background;
			}
			}

			// Create a hash for this combination of background settings.
			// This is used to determine when two slide backgrounds are
			// the same.
			if( data.background \|\| data.backgroundColor \|\| data.backgroundImage \|\| data.backgroundVideo \|\| data.backgroundIframe ) {
			element.setAttribute( 'data-background-hash', data.background +
			data.backgroundSize +
			data.backgroundImage +
			data.backgroundVideo +
			data.backgroundIframe +
			data.backgroundColor +
			data.backgroundRepeat +
			data.backgroundPosition +
			data.backgroundTransition );
			}

			// Additional and optional background properties
			if( data.backgroundSize ) element.style.backgroundSize = data.backgroundSize;
			if( data.backgroundSize ) element.setAttribute( 'data-background-size', data.backgroundSize );
			if( data.backgroundColor ) element.style.backgroundColor = data.backgroundColor;
			if( data.backgroundRepeat ) element.style.backgroundRepeat = data.backgroundRepeat;
			if( data.backgroundPosition ) element.style.backgroundPosition = data.backgroundPosition;
			if( data.backgroundTransition ) element.setAttribute( 'data-background-transition', data.backgroundTransition );

			container.appendChild( element );

			// If backgrounds are being recreated, clear old classes
			slide.classList.remove( 'has-dark-background' );
			slide.classList.remove( 'has-light-background' );

			slide.slideBackgroundElement = element;

			// If this slide has a background color, add a class that
			// signals if it is light or dark. If the slide has no background
			// color, no class will be set
			var computedBackgroundStyle = window.getComputedStyle( element );
			if( computedBackgroundStyle && computedBackgroundStyle.backgroundColor ) {
			var rgb = colorToRgb( computedBackgroundStyle.backgroundColor );

			// Ignore fully transparent backgrounds. Some browsers return
			// rgba(0,0,0,0) when reading the computed background color of
			// an element with no background
			if( rgb && rgb.a !== 0 ) {
			if( colorBrightness( computedBackgroundStyle.backgroundColor ) < 128 ) {
			slide.classList.add( 'has-dark-background' );
			}
			else {
			slide.classList.add( 'has-light-background' );
			}
			}
			}

			return element;

			}

			/**
			* Registers a listener to postMessage events, this makes it
			* possible to call all reveal.js API methods from another
			* window. For example:
			*
			* revealWindow.postMessage( JSON.stringify({
			* method: 'slide',
			* args: [ 2 ]
			* }), '*' );
			*/
			function setupPostMessage() {

			if( config.postMessage ) {
			window.addEventListener( 'message', function ( event ) {
			var data = event.data;

			// Make sure we're dealing with JSON
			if( typeof data === 'string' && data.charAt( 0 ) === '{' && data.charAt( data.length - 1 ) === '}' ) {
			data = JSON.parse( data );

			// Check if the requested method can be found
			if( data.method && typeof Reveal[data.method] === 'function' ) {
			Reveal[data.method].apply( Reveal, data.args );
			}
			}
			}, false );
			}

			}

			/**
			* Applies the configuration settings from the config
			* object. May be called multiple times.
			*
			* @param {object} options
			*/
			function configure( options ) {

			var numberOfSlides = dom.wrapper.querySelectorAll( SLIDES_SELECTOR ).length;

			dom.wrapper.classList.remove( config.transition );

			// New config options may be passed when this method
			// is invoked through the API after initialization
			if( typeof options === 'object' ) extend( config, options );

			// Force linear transition based on browser capabilities
			if( features.transforms3d === false ) config.transition = 'linear';

			dom.wrapper.classList.add( config.transition );

			dom.wrapper.setAttribute( 'data-transition-speed', config.transitionSpeed );
			dom.wrapper.setAttribute( 'data-background-transition', config.backgroundTransition );

			dom.controls.style.display = config.controls ? 'block' : 'none';
			dom.progress.style.display = config.progress ? 'block' : 'none';

			if( config.shuffle ) {
			shuffle();
			}

			if( config.rtl ) {
			dom.wrapper.classList.add( 'rtl' );
			}
			else {
			dom.wrapper.classList.remove( 'rtl' );
			}

			if( config.center ) {
			dom.wrapper.classList.add( 'center' );
			}
			else {
			dom.wrapper.classList.remove( 'center' );
			}

			// Exit the paused mode if it was configured off
			if( config.pause === false ) {
			resume();
			}

			if( config.showNotes ) {
			dom.speakerNotes.classList.add( 'visible' );
			dom.speakerNotes.setAttribute( 'data-layout', typeof config.showNotes === 'string' ? config.showNotes : 'inline' );
			}
			else {
			dom.speakerNotes.classList.remove( 'visible' );
			}

			if( config.mouseWheel ) {
			document.addEventListener( 'DOMMouseScroll', onDocumentMouseScroll, false ); // FF
			document.addEventListener( 'mousewheel', onDocumentMouseScroll, false );
			}
			else {
			document.removeEventListener( 'DOMMouseScroll', onDocumentMouseScroll, false ); // FF
			document.removeEventListener( 'mousewheel', onDocumentMouseScroll, false );
			}

			// Rolling 3D links
			if( config.rollingLinks ) {
			enableRollingLinks();
			}
			else {
			disableRollingLinks();
			}

			// Iframe link previews
			if( config.previewLinks ) {
			enablePreviewLinks();
			disablePreviewLinks( '[data-preview-link=false]' );
			}
			else {
			disablePreviewLinks();
			enablePreviewLinks( '[data-preview-link]:not([data-preview-link=false])' );
			}

			// Remove existing auto-slide controls
			if( autoSlidePlayer ) {
			autoSlidePlayer.destroy();
			autoSlidePlayer = null;
			}

			// Generate auto-slide controls if needed
			if( numberOfSlides > 1 && config.autoSlide && config.autoSlideStoppable && features.canvas && features.requestAnimationFrame ) {
			autoSlidePlayer = new Playback( dom.wrapper, function() {
			return Math.min( Math.max( ( Date.now() - autoSlideStartTime ) / autoSlide, 0 ), 1 );
			} );

			autoSlidePlayer.on( 'click', onAutoSlidePlayerClick );
			autoSlidePaused = false;
			}

			// When fragments are turned off they should be visible
			if( config.fragments === false ) {
			toArray( dom.slides.querySelectorAll( '.fragment' ) ).forEach( function( element ) {
			element.classList.add( 'visible' );
			element.classList.remove( 'current-fragment' );
			} );
			}

			// Slide numbers
			var slideNumberDisplay = 'none';
			if( config.slideNumber && !isPrintingPDF() ) {
			if( config.showSlideNumber === 'all' ) {
			slideNumberDisplay = 'block';
			}
			else if( config.showSlideNumber === 'speaker' && isSpeakerNotes() ) {
			slideNumberDisplay = 'block';
			}
			}

			dom.slideNumber.style.display = slideNumberDisplay;

			sync();

			}

			/**
			* Binds all event listeners.
			*/
			function addEventListeners() {

			eventsAreBound = true;

			window.addEventListener( 'hashchange', onWindowHashChange, false );
			window.addEventListener( 'resize', onWindowResize, false );

			if( config.touch ) {
			dom.wrapper.addEventListener( 'touchstart', onTouchStart, false );
			dom.wrapper.addEventListener( 'touchmove', onTouchMove, false );
			dom.wrapper.addEventListener( 'touchend', onTouchEnd, false );

			// Support pointer-style touch interaction as well
			if( window.navigator.pointerEnabled ) {
			// IE 11 uses un-prefixed version of pointer events
			dom.wrapper.addEventListener( 'pointerdown', onPointerDown, false );
			dom.wrapper.addEventListener( 'pointermove', onPointerMove, false );
			dom.wrapper.addEventListener( 'pointerup', onPointerUp, false );
			}
			else if( window.navigator.msPointerEnabled ) {
			// IE 10 uses prefixed version of pointer events
			dom.wrapper.addEventListener( 'MSPointerDown', onPointerDown, false );
			dom.wrapper.addEventListener( 'MSPointerMove', onPointerMove, false );
			dom.wrapper.addEventListener( 'MSPointerUp', onPointerUp, false );
			}
			}

			if( config.keyboard ) {
			document.addEventListener( 'keydown', onDocumentKeyDown, false );
			document.addEventListener( 'keypress', onDocumentKeyPress, false );
			}

			if( config.progress && dom.progress ) {
			dom.progress.addEventListener( 'click', onProgressClicked, false );
			}

			if( config.focusBodyOnPageVisibilityChange ) {
			var visibilityChange;

			if( 'hidden' in document ) {
			visibilityChange = 'visibilitychange';
			}
			else if( 'msHidden' in document ) {
			visibilityChange = 'msvisibilitychange';
			}
			else if( 'webkitHidden' in document ) {
			visibilityChange = 'webkitvisibilitychange';
			}

			if( visibilityChange ) {
			document.addEventListener( visibilityChange, onPageVisibilityChange, false );
			}
			}

			// Listen to both touch and click events, in case the device
			// supports both
			var pointerEvents = [ 'touchstart', 'click' ];

			// Only support touch for Android, fixes double navigations in
			// stock browser
			if( UA.match( /android/gi ) ) {
			pointerEvents = [ 'touchstart' ];
			}

			pointerEvents.forEach( function( eventName ) {
			dom.controlsLeft.forEach( function( el ) { el.addEventListener( eventName, onNavigateLeftClicked, false ); } );
			dom.controlsRight.forEach( function( el ) { el.addEventListener( eventName, onNavigateRightClicked, false ); } );
			dom.controlsUp.forEach( function( el ) { el.addEventListener( eventName, onNavigateUpClicked, false ); } );
			dom.controlsDown.forEach( function( el ) { el.addEventListener( eventName, onNavigateDownClicked, false ); } );
			dom.controlsPrev.forEach( function( el ) { el.addEventListener( eventName, onNavigatePrevClicked, false ); } );
			dom.controlsNext.forEach( function( el ) { el.addEventListener( eventName, onNavigateNextClicked, false ); } );
			} );

			}

			/**
			* Unbinds all event listeners.
			*/
			function removeEventListeners() {

			eventsAreBound = false;

			document.removeEventListener( 'keydown', onDocumentKeyDown, false );
			document.removeEventListener( 'keypress', onDocumentKeyPress, false );
			window.removeEventListener( 'hashchange', onWindowHashChange, false );
			window.removeEventListener( 'resize', onWindowResize, false );

			dom.wrapper.removeEventListener( 'touchstart', onTouchStart, false );
			dom.wrapper.removeEventListener( 'touchmove', onTouchMove, false );
			dom.wrapper.removeEventListener( 'touchend', onTouchEnd, false );

			// IE11
			if( window.navigator.pointerEnabled ) {
			dom.wrapper.removeEventListener( 'pointerdown', onPointerDown, false );
			dom.wrapper.removeEventListener( 'pointermove', onPointerMove, false );
			dom.wrapper.removeEventListener( 'pointerup', onPointerUp, false );
			}
			// IE10
			else if( window.navigator.msPointerEnabled ) {
			dom.wrapper.removeEventListener( 'MSPointerDown', onPointerDown, false );
			dom.wrapper.removeEventListener( 'MSPointerMove', onPointerMove, false );
			dom.wrapper.removeEventListener( 'MSPointerUp', onPointerUp, false );
			}

			if ( config.progress && dom.progress ) {
			dom.progress.removeEventListener( 'click', onProgressClicked, false );
			}

			[ 'touchstart', 'click' ].forEach( function( eventName ) {
			dom.controlsLeft.forEach( function( el ) { el.removeEventListener( eventName, onNavigateLeftClicked, false ); } );
			dom.controlsRight.forEach( function( el ) { el.removeEventListener( eventName, onNavigateRightClicked, false ); } );
			dom.controlsUp.forEach( function( el ) { el.removeEventListener( eventName, onNavigateUpClicked, false ); } );
			dom.controlsDown.forEach( function( el ) { el.removeEventListener( eventName, onNavigateDownClicked, false ); } );
			dom.controlsPrev.forEach( function( el ) { el.removeEventListener( eventName, onNavigatePrevClicked, false ); } );
			dom.controlsNext.forEach( function( el ) { el.removeEventListener( eventName, onNavigateNextClicked, false ); } );
			} );

			}

			/**
			* Extend object a with the properties of object b.
			* If there's a conflict, object b takes precedence.
			*
			* @param {object} a
			* @param {object} b
			*/
			function extend( a, b ) {

			for( var i in b ) {
			a[ i ] = b[ i ];
			}

			}

			/**
			* Converts the target object to an array.
			*
			* @param {object} o
			* @return {object[]}
			*/
			function toArray( o ) {

			return Array.prototype.slice.call( o );

			}

			/**
			* Utility for deserializing a value.
			*
			* @param {*} value
			* @return {*}
			*/
			function deserialize( value ) {

			if( typeof value === 'string' ) {
			if( value === 'null' ) return null;
			else if( value === 'true' ) return true;
			else if( value === 'false' ) return false;
			else if( value.match( /^[\d\.]+$/ ) ) return parseFloat( value );
			}

			return value;

			}

			/**
			* Measures the distance in pixels between point a
			* and point b.
			*
			* @param {object} a point with x/y properties
			* @param {object} b point with x/y properties
			*
			* @return {number}
			*/
			function distanceBetween( a, b ) {

			var dx = a.x - b.x,
			dy = a.y - b.y;

			return Math.sqrt( dxdx + dydy );

			}

			/**
			* Applies a CSS transform to the target element.
			*
			* @param {HTMLElement} element
			* @param {string} transform
			*/
			function transformElement( element, transform ) {

			element.style.WebkitTransform = transform;
			element.style.MozTransform = transform;
			element.style.msTransform = transform;
			element.style.transform = transform;

			}

			/**
			* Applies CSS transforms to the slides container. The container
			* is transformed from two separate sources: layout and the overview
			* mode.
			*
			* @param {object} transforms
			*/
			function transformSlides( transforms ) {

			// Pick up new transforms from arguments
			if( typeof transforms.layout === 'string' ) slidesTransform.layout = transforms.layout;
			if( typeof transforms.overview === 'string' ) slidesTransform.overview = transforms.overview;

			// Apply the transforms to the slides container
			if( slidesTransform.layout ) {
			transformElement( dom.slides, slidesTransform.layout + ' ' + slidesTransform.overview );
			}
			else {
			transformElement( dom.slides, slidesTransform.overview );
			}

			}

			/**
			* Injects the given CSS styles into the DOM.
			*
			* @param {string} value
			*/
			function injectStyleSheet( value ) {

			var tag = document.createElement( 'style' );
			tag.type = 'text/css';
			if( tag.styleSheet ) {
			tag.styleSheet.cssText = value;
			}
			else {
			tag.appendChild( document.createTextNode( value ) );
			}
			document.getElementsByTagName( 'head' )[0].appendChild( tag );

			}

			/**
			* Find the closest parent that matches the given
			* selector.
			*
			* @param {HTMLElement} target The child element
			* @param {String} selector The CSS selector to match
			* the parents against
			*
			* @return {HTMLElement} The matched parent or null
			* if no matching parent was found
			*/
			function closestParent( target, selector ) {

			var parent = target.parentNode;

			while( parent ) {

			// There's some overhead doing this each time, we don't
			// want to rewrite the element prototype but should still
			// be enough to feature detect once at startup...
			var matchesMethod = parent.matches \|\| parent.matchesSelector \|\| parent.msMatchesSelector;

			// If we find a match, we're all set
			if( matchesMethod && matchesMethod.call( parent, selector ) ) {
			return parent;
			}

			// Keep searching
			parent = parent.parentNode;

			}

			return null;

			}

			/**
			* Converts various color input formats to an {r:0,g:0,b:0} object.
			*
			* @param {string} color The string representation of a color
			* @example
			* colorToRgb('#000');
			* @example
			* colorToRgb('#000000');
			* @example
			* colorToRgb('rgb(0,0,0)');
			* @example
			* colorToRgb('rgba(0,0,0)');
			*
			* @return {{r: number, g: number, b: number, [a]: number}\|null}
			*/
			function colorToRgb( color ) {

			var hex3 = color.match( /^#([0-9a-f]{3})$/i );
			if( hex3 && hex3[1] ) {
			hex3 = hex3[1];
			return {
			r: parseInt( hex3.charAt( 0 ), 16 ) * 0x11,
			g: parseInt( hex3.charAt( 1 ), 16 ) * 0x11,
			b: parseInt( hex3.charAt( 2 ), 16 ) * 0x11
			};
			}

			var hex6 = color.match( /^#([0-9a-f]{6})$/i );
			if( hex6 && hex6[1] ) {
			hex6 = hex6[1];
			return {
			r: parseInt( hex6.substr( 0, 2 ), 16 ),
			g: parseInt( hex6.substr( 2, 2 ), 16 ),
			b: parseInt( hex6.substr( 4, 2 ), 16 )
			};
			}

			var rgb = color.match( /^rgb\s$\s(\d+)\s,\s(\d+)\s,\s(\d+)\s*$$/i );
			if( rgb ) {
			return {
			r: parseInt( rgb[1], 10 ),
			g: parseInt( rgb[2], 10 ),
			b: parseInt( rgb[3], 10 )
			};
			}

			var rgba = color.match( /^rgba\s$\s(\d+)\s,\s(\d+)\s,\s(\d+)\s\,\s([\d]+\|[\d].[\d]+)\s$$/i );
			if( rgba ) {
			return {
			r: parseInt( rgba[1], 10 ),
			g: parseInt( rgba[2], 10 ),
			b: parseInt( rgba[3], 10 ),
			a: parseFloat( rgba[4] )
			};
			}

			return null;

			}

			/**
			* Calculates brightness on a scale of 0-255.
			*
			* @param {string} color See colorToRgb for supported formats.
			* @see {@link colorToRgb}
			*/
			function colorBrightness( color ) {

			if( typeof color === 'string' ) color = colorToRgb( color );

			if( color ) {
			return ( color.r * 299 + color.g * 587 + color.b * 114 ) / 1000;
			}

			return null;

			}

			/**
			* Returns the remaining height within the parent of the
			* target element.
			*
			* remaining height = [ configured parent height ] - [ current parent height ]
			*
			* @param {HTMLElement} element
			* @param {number} [height]
			*/
			function getRemainingHeight( element, height ) {

			height = height \|\| 0;

			if( element ) {
			var newHeight, oldHeight = element.style.height;

			// Change the .stretch element height to 0 in order find the height of all
			// the other elements
			element.style.height = '0px';
			newHeight = height - element.parentNode.offsetHeight;

			// Restore the old height, just in case
			element.style.height = oldHeight + 'px';

			return newHeight;
			}

			return height;

			}

			/**
			* Checks if this instance is being used to print a PDF.
			*/
			function isPrintingPDF() {

			return ( /print-pdf/gi ).test( window.location.search );

			}

			/**
			* Hides the address bar if we're on a mobile device.
			*/
			function hideAddressBar() {

			if( config.hideAddressBar && isMobileDevice ) {
			// Events that should trigger the address bar to hide
			window.addEventListener( 'load', removeAddressBar, false );
			window.addEventListener( 'orientationchange', removeAddressBar, false );
			}

			}

			/**
			* Causes the address bar to hide on mobile devices,
			* more vertical space ftw.
			*/
			function removeAddressBar() {

			setTimeout( function() {
			window.scrollTo( 0, 1 );
			}, 10 );

			}

			/**
			* Dispatches an event of the specified type from the
			* reveal DOM element.
			*/
			function dispatchEvent( type, args ) {

			var event = document.createEvent( 'HTMLEvents', 1, 2 );
			event.initEvent( type, true, true );
			extend( event, args );
			dom.wrapper.dispatchEvent( event );

			// If we're in an iframe, post each reveal.js event to the
			// parent window. Used by the notes plugin
			if( config.postMessageEvents && window.parent !== window.self ) {
			window.parent.postMessage( JSON.stringify({ namespace: 'reveal', eventName: type, state: getState() }), '*' );
			}

			}

			/**
			* Wrap all links in 3D goodness.
			*/
			function enableRollingLinks() {

			if( features.transforms3d && !( 'msPerspective' in document.body.style ) ) {
			var anchors = dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ' a' );

			for( var i = 0, len = anchors.length; i < len; i++ ) {
			var anchor = anchors[i];

			if( anchor.textContent && !anchor.querySelector( '*' ) && ( !anchor.className \|\| !anchor.classList.contains( anchor, 'roll' ) ) ) {
			var span = document.createElement('span');
			span.setAttribute('data-title', anchor.text);
			span.innerHTML = anchor.innerHTML;

			anchor.classList.add( 'roll' );
			anchor.innerHTML = '';
			anchor.appendChild(span);
			}
			}
			}

			}

			/**
			* Unwrap all 3D links.
			*/
			function disableRollingLinks() {

			var anchors = dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ' a.roll' );

			for( var i = 0, len = anchors.length; i < len; i++ ) {
			var anchor = anchors[i];
			var span = anchor.querySelector( 'span' );

			if( span ) {
			anchor.classList.remove( 'roll' );
			anchor.innerHTML = span.innerHTML;
			}
			}

			}

			/**
			* Bind preview frame links.
			*
			* @param {string} [selector=a] - selector for anchors
			*/
			function enablePreviewLinks( selector ) {

			var anchors = toArray( document.querySelectorAll( selector ? selector : 'a' ) );

			anchors.forEach( function( element ) {
			if( /^(http\|www)/gi.test( element.getAttribute( 'href' ) ) ) {
			element.addEventListener( 'click', onPreviewLinkClicked, false );
			}
			} );

			}

			/**
			* Unbind preview frame links.
			*/
			function disablePreviewLinks( selector ) {

			var anchors = toArray( document.querySelectorAll( selector ? selector : 'a' ) );

			anchors.forEach( function( element ) {
			if( /^(http\|www)/gi.test( element.getAttribute( 'href' ) ) ) {
			element.removeEventListener( 'click', onPreviewLinkClicked, false );
			}
			} );

			}

			/**
			* Opens a preview window for the target URL.
			*
			* @param {string} url - url for preview iframe src
			*/
			function showPreview( url ) {

			closeOverlay();

			dom.overlay = document.createElement( 'div' );
			dom.overlay.classList.add( 'overlay' );
			dom.overlay.classList.add( 'overlay-preview' );
			dom.wrapper.appendChild( dom.overlay );

			dom.overlay.innerHTML = [
			'<header>',
			'<a class="close" href="#"><span class="icon"></span></a>',
			'<a class="external" href="'+ url +'" target="_blank"><span class="icon"></span></a>',
			'</header>',
			'<div class="spinner"></div>',
			'<div class="viewport">',
			'<iframe src="'+ url +'"></iframe>',
			'<small class="viewport-inner">',
			'<span class="x-frame-error">Unable to load iframe. This is likely due to the site\'s policy (x-frame-options).</span>',
			'</small>',
			'</div>'
			].join('');

			dom.overlay.querySelector( 'iframe' ).addEventListener( 'load', function( event ) {
			dom.overlay.classList.add( 'loaded' );
			}, false );

			dom.overlay.querySelector( '.close' ).addEventListener( 'click', function( event ) {
			closeOverlay();
			event.preventDefault();
			}, false );

			dom.overlay.querySelector( '.external' ).addEventListener( 'click', function( event ) {
			closeOverlay();
			}, false );

			setTimeout( function() {
			dom.overlay.classList.add( 'visible' );
			}, 1 );

			}

			/**
			* Open or close help overlay window.
			*
			* @param {Boolean} [override] Flag which overrides the
			* toggle logic and forcibly sets the desired state. True means
			* help is open, false means it's closed.
			*/
			function toggleHelp( override ){

			if( typeof override === 'boolean' ) {
			override ? showHelp() : closeOverlay();
			}
			else {
			if( dom.overlay ) {
			closeOverlay();
			}
			else {
			showHelp();
			}
			}
			}

			/**
			* Opens an overlay window with help material.
			*/
			function showHelp() {

			if( config.help ) {

			closeOverlay();

			dom.overlay = document.createElement( 'div' );
			dom.overlay.classList.add( 'overlay' );
			dom.overlay.classList.add( 'overlay-help' );
			dom.wrapper.appendChild( dom.overlay );

			var html = '<p class="title">Keyboard Shortcuts</p><br/>';

			html += '<table><th>KEY</th><th>ACTION</th>';
			for( var key in keyboardShortcuts ) {
			html += '<tr><td>' + key + '</td><td>' + keyboardShortcuts[ key ] + '</td></tr>';
			}

			html += '</table>';

			dom.overlay.innerHTML = [
			'<header>',
			'<a class="close" href="#"><span class="icon"></span></a>',
			'</header>',
			'<div class="viewport">',
			'<div class="viewport-inner">'+ html +'</div>',
			'</div>'
			].join('');

			dom.overlay.querySelector( '.close' ).addEventListener( 'click', function( event ) {
			closeOverlay();
			event.preventDefault();
			}, false );

			setTimeout( function() {
			dom.overlay.classList.add( 'visible' );
			}, 1 );

			}

			}

			/**
			* Closes any currently open overlay.
			*/
			function closeOverlay() {

			if( dom.overlay ) {
			dom.overlay.parentNode.removeChild( dom.overlay );
			dom.overlay = null;
			}

			}

			/**
			* Applies JavaScript-controlled layout rules to the
			* presentation.
			*/
			function layout() {

			if( dom.wrapper && !isPrintingPDF() ) {

			var size = getComputedSlideSize();

			// Layout the contents of the slides
			layoutSlideContents( config.width, config.height );

			dom.slides.style.width = size.width + 'px';
			dom.slides.style.height = size.height + 'px';

			// Determine scale of content to fit within available space
			scale = Math.min( size.presentationWidth / size.width, size.presentationHeight / size.height );

			// Respect max/min scale settings
			scale = Math.max( scale, config.minScale );
			scale = Math.min( scale, config.maxScale );

			// Don't apply any scaling styles if scale is 1
			if( scale === 1 ) {
			dom.slides.style.zoom = '';
			dom.slides.style.left = '';
			dom.slides.style.top = '';
			dom.slides.style.bottom = '';
			dom.slides.style.right = '';
			transformSlides( { layout: '' } );
			}
			else {
			// Prefer zoom for scaling up so that content remains crisp.
			// Don't use zoom to scale down since that can lead to shifts
			// in text layout/line breaks.
			if( scale > 1 && features.zoom ) {
			dom.slides.style.zoom = scale;
			dom.slides.style.left = '';
			dom.slides.style.top = '';
			dom.slides.style.bottom = '';
			dom.slides.style.right = '';
			transformSlides( { layout: '' } );
			}
			// Apply scale transform as a fallback
			else {
			dom.slides.style.zoom = '';
			dom.slides.style.left = '50%';
			dom.slides.style.top = '50%';
			dom.slides.style.bottom = 'auto';
			dom.slides.style.right = 'auto';
			transformSlides( { layout: 'translate(-50%, -50%) scale('+ scale +')' } );
			}
			}

			// Select all slides, vertical and horizontal
			var slides = toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) );

			for( var i = 0, len = slides.length; i < len; i++ ) {
			var slide = slides[ i ];

			// Don't bother updating invisible slides
			if( slide.style.display === 'none' ) {
			continue;
			}

			if( config.center \|\| slide.classList.contains( 'center' ) ) {
			// Vertical stacks are not centred since their section
			// children will be
			if( slide.classList.contains( 'stack' ) ) {
			slide.style.top = 0;
			}
			else {
			slide.style.top = Math.max( ( size.height - slide.scrollHeight ) / 2, 0 ) + 'px';
			}
			}
			else {
			slide.style.top = '';
			}

			}

			updateProgress();
			updateParallax();

			if( isOverview() ) {
			updateOverview();
			}

			}

			}

			/**
			* Applies layout logic to the contents of all slides in
			* the presentation.
			*
			* @param {string\|number} width
			* @param {string\|number} height
			*/
			function layoutSlideContents( width, height ) {

			// Handle sizing of elements with the 'stretch' class
			toArray( dom.slides.querySelectorAll( 'section > .stretch' ) ).forEach( function( element ) {

			// Determine how much vertical space we can use
			var remainingHeight = getRemainingHeight( element, height );

			// Consider the aspect ratio of media elements
			if( /(img\|video)/gi.test( element.nodeName ) ) {
			var nw = element.naturalWidth \|\| element.videoWidth,
			nh = element.naturalHeight \|\| element.videoHeight;

			var es = Math.min( width / nw, remainingHeight / nh );

			element.style.width = ( nw * es ) + 'px';
			element.style.height = ( nh * es ) + 'px';

			}
			else {
			element.style.width = width + 'px';
			element.style.height = remainingHeight + 'px';
			}

			} );

			}

			/**
			* Calculates the computed pixel size of our slides. These
			* values are based on the width and height configuration
			* options.
			*
			* @param {number} [presentationWidth=dom.wrapper.offsetWidth]
			* @param {number} [presentationHeight=dom.wrapper.offsetHeight]
			*/
			function getComputedSlideSize( presentationWidth, presentationHeight ) {

			var size = {
			// Slide size
			width: config.width,
			height: config.height,

			// Presentation size
			presentationWidth: presentationWidth \|\| dom.wrapper.offsetWidth,
			presentationHeight: presentationHeight \|\| dom.wrapper.offsetHeight
			};

			// Reduce available space by margin
			size.presentationWidth -= ( size.presentationWidth * config.margin );
			size.presentationHeight -= ( size.presentationHeight * config.margin );

			// Slide width may be a percentage of available width
			if( typeof size.width === 'string' && /%$/.test( size.width ) ) {
			size.width = parseInt( size.width, 10 ) / 100 * size.presentationWidth;
			}

			// Slide height may be a percentage of available height
			if( typeof size.height === 'string' && /%$/.test( size.height ) ) {
			size.height = parseInt( size.height, 10 ) / 100 * size.presentationHeight;
			}

			return size;

			}

			/**
			* Stores the vertical index of a stack so that the same
			* vertical slide can be selected when navigating to and
			* from the stack.
			*
			* @param {HTMLElement} stack The vertical stack element
			* @param {string\|number} [v=0] Index to memorize
			*/
			function setPreviousVerticalIndex( stack, v ) {

			if( typeof stack === 'object' && typeof stack.setAttribute === 'function' ) {
			stack.setAttribute( 'data-previous-indexv', v \|\| 0 );
			}

			}

			/**
			* Retrieves the vertical index which was stored using
			* #setPreviousVerticalIndex() or 0 if no previous index
			* exists.
			*
			* @param {HTMLElement} stack The vertical stack element
			*/
			function getPreviousVerticalIndex( stack ) {

			if( typeof stack === 'object' && typeof stack.setAttribute === 'function' && stack.classList.contains( 'stack' ) ) {
			// Prefer manually defined start-indexv
			var attributeName = stack.hasAttribute( 'data-start-indexv' ) ? 'data-start-indexv' : 'data-previous-indexv';

			return parseInt( stack.getAttribute( attributeName ) \|\| 0, 10 );
			}

			return 0;

			}

			/**
			* Displays the overview of slides (quick nav) by scaling
			* down and arranging all slide elements.
			*/
			function activateOverview() {

			// Only proceed if enabled in config
			if( config.overview && !isOverview() ) {

			overview = true;

			dom.wrapper.classList.add( 'overview' );
			dom.wrapper.classList.remove( 'overview-deactivating' );

			if( features.overviewTransitions ) {
			setTimeout( function() {
			dom.wrapper.classList.add( 'overview-animated' );
			}, 1 );
			}

			// Don't auto-slide while in overview mode
			cancelAutoSlide();

			// Move the backgrounds element into the slide container to
			// that the same scaling is applied
			dom.slides.appendChild( dom.background );

			// Clicking on an overview slide navigates to it
			toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) ).forEach( function( slide ) {
			if( !slide.classList.contains( 'stack' ) ) {
			slide.addEventListener( 'click', onOverviewSlideClicked, true );
			}
			} );

			// Calculate slide sizes
			var margin = 70;
			var slideSize = getComputedSlideSize();
			overviewSlideWidth = slideSize.width + margin;
			overviewSlideHeight = slideSize.height + margin;

			// Reverse in RTL mode
			if( config.rtl ) {
			overviewSlideWidth = -overviewSlideWidth;
			}

			updateSlidesVisibility();
			layoutOverview();
			updateOverview();

			layout();

			// Notify observers of the overview showing
			dispatchEvent( 'overviewshown', {
			'indexh': indexh,
			'indexv': indexv,
			'currentSlide': currentSlide
			} );

			}

			}

			/**
			* Uses CSS transforms to position all slides in a grid for
			* display inside of the overview mode.
			*/
			function layoutOverview() {

			// Layout slides
			toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( hslide, h ) {
			hslide.setAttribute( 'data-index-h', h );
			transformElement( hslide, 'translate3d(' + ( h * overviewSlideWidth ) + 'px, 0, 0)' );

			if( hslide.classList.contains( 'stack' ) ) {

			toArray( hslide.querySelectorAll( 'section' ) ).forEach( function( vslide, v ) {
			vslide.setAttribute( 'data-index-h', h );
			vslide.setAttribute( 'data-index-v', v );

			transformElement( vslide, 'translate3d(0, ' + ( v * overviewSlideHeight ) + 'px, 0)' );
			} );

			}
			} );

			// Layout slide backgrounds
			toArray( dom.background.childNodes ).forEach( function( hbackground, h ) {
			transformElement( hbackground, 'translate3d(' + ( h * overviewSlideWidth ) + 'px, 0, 0)' );

			toArray( hbackground.querySelectorAll( '.slide-background' ) ).forEach( function( vbackground, v ) {
			transformElement( vbackground, 'translate3d(0, ' + ( v * overviewSlideHeight ) + 'px, 0)' );
			} );
			} );

			}

			/**
			* Moves the overview viewport to the current slides.
			* Called each time the current slide changes.
			*/
			function updateOverview() {

			var vmin = Math.min( window.innerWidth, window.innerHeight );
			var scale = Math.max( vmin / 5, 150 ) / vmin;

			transformSlides( {
			overview: [
			'scale('+ scale +')',
			'translateX('+ ( -indexh * overviewSlideWidth ) +'px)',
			'translateY('+ ( -indexv * overviewSlideHeight ) +'px)'
			].join( ' ' )
			} );

			}

			/**
			* Exits the slide overview and enters the currently
			* active slide.
			*/
			function deactivateOverview() {

			// Only proceed if enabled in config
			if( config.overview ) {

			overview = false;

			dom.wrapper.classList.remove( 'overview' );
			dom.wrapper.classList.remove( 'overview-animated' );

			// Temporarily add a class so that transitions can do different things
			// depending on whether they are exiting/entering overview, or just
			// moving from slide to slide
			dom.wrapper.classList.add( 'overview-deactivating' );

			setTimeout( function () {
			dom.wrapper.classList.remove( 'overview-deactivating' );
			}, 1 );

			// Move the background element back out
			dom.wrapper.appendChild( dom.background );

			// Clean up changes made to slides
			toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) ).forEach( function( slide ) {
			transformElement( slide, '' );

			slide.removeEventListener( 'click', onOverviewSlideClicked, true );
			} );

			// Clean up changes made to backgrounds
			toArray( dom.background.querySelectorAll( '.slide-background' ) ).forEach( function( background ) {
			transformElement( background, '' );
			} );

			transformSlides( { overview: '' } );

			slide( indexh, indexv );

			layout();

			cueAutoSlide();

			// Notify observers of the overview hiding
			dispatchEvent( 'overviewhidden', {
			'indexh': indexh,
			'indexv': indexv,
			'currentSlide': currentSlide
			} );

			}
			}

			/**
			* Toggles the slide overview mode on and off.
			*
			* @param {Boolean} [override] Flag which overrides the
			* toggle logic and forcibly sets the desired state. True means
			* overview is open, false means it's closed.
			*/
			function toggleOverview( override ) {

			if( typeof override === 'boolean' ) {
			override ? activateOverview() : deactivateOverview();
			}
			else {
			isOverview() ? deactivateOverview() : activateOverview();
			}

			}

			/**
			* Checks if the overview is currently active.
			*
			* @return {Boolean} true if the overview is active,
			* false otherwise
			*/
			function isOverview() {

			return overview;

			}

			/**
			* Checks if the current or specified slide is vertical
			* (nested within another slide).
			*
			* @param {HTMLElement} [slide=currentSlide] The slide to check
			* orientation of
			* @return {Boolean}
			*/
			function isVerticalSlide( slide ) {

			// Prefer slide argument, otherwise use current slide
			slide = slide ? slide : currentSlide;

			return slide && slide.parentNode && !!slide.parentNode.nodeName.match( /section/i );

			}

			/**
			* Handling the fullscreen functionality via the fullscreen API
			*
			* @see http://fullscreen.spec.whatwg.org/
			* @see https://developer.mozilla.org/en-US/docs/DOM/Using_fullscreen_mode
			*/
			function enterFullscreen() {

			var element = document.documentElement;

			// Check which implementation is available
			var requestMethod = element.requestFullscreen \|\|
			element.webkitRequestFullscreen \|\|
			element.webkitRequestFullScreen \|\|
			element.mozRequestFullScreen \|\|
			element.msRequestFullscreen;

			if( requestMethod ) {
			requestMethod.apply( element );
			}

			}

			/**
			* Enters the paused mode which fades everything on screen to
			* black.
			*/
			function pause() {

			if( config.pause ) {
			var wasPaused = dom.wrapper.classList.contains( 'paused' );

			cancelAutoSlide();
			dom.wrapper.classList.add( 'paused' );

			if( wasPaused === false ) {
			dispatchEvent( 'paused' );
			}
			}

			}

			/**
			* Exits from the paused mode.
			*/
			function resume() {

			var wasPaused = dom.wrapper.classList.contains( 'paused' );
			dom.wrapper.classList.remove( 'paused' );

			cueAutoSlide();

			if( wasPaused ) {
			dispatchEvent( 'resumed' );
			}

			}

			/**
			* Toggles the paused mode on and off.
			*/
			function togglePause( override ) {

			if( typeof override === 'boolean' ) {
			override ? pause() : resume();
			}
			else {
			isPaused() ? resume() : pause();
			}

			}

			/**
			* Checks if we are currently in the paused mode.
			*
			* @return {Boolean}
			*/
			function isPaused() {

			return dom.wrapper.classList.contains( 'paused' );

			}

			/**
			* Toggles the auto slide mode on and off.
			*
			* @param {Boolean} [override] Flag which sets the desired state.
			* True means autoplay starts, false means it stops.
			*/

			function toggleAutoSlide( override ) {

			if( typeof override === 'boolean' ) {
			override ? resumeAutoSlide() : pauseAutoSlide();
			}

			else {
			autoSlidePaused ? resumeAutoSlide() : pauseAutoSlide();
			}

			}

			/**
			* Checks if the auto slide mode is currently on.
			*
			* @return {Boolean}
			*/
			function isAutoSliding() {

			return !!( autoSlide && !autoSlidePaused );

			}

			/**
			* Steps from the current point in the presentation to the
			* slide which matches the specified horizontal and vertical
			* indices.
			*
			* @param {number} [h=indexh] Horizontal index of the target slide
			* @param {number} [v=indexv] Vertical index of the target slide
			* @param {number} [f] Index of a fragment within the
			* target slide to activate
			* @param {number} [o] Origin for use in multimaster environments
			*/
			function slide( h, v, f, o ) {

			// Remember where we were at before
			previousSlide = currentSlide;

			// Query all horizontal slides in the deck
			var horizontalSlides = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR );

			// Abort if there are no slides
			if( horizontalSlides.length === 0 ) return;

			// If no vertical index is specified and the upcoming slide is a
			// stack, resume at its previous vertical index
			if( v === undefined && !isOverview() ) {
			v = getPreviousVerticalIndex( horizontalSlides[ h ] );
			}

			// If we were on a vertical stack, remember what vertical index
			// it was on so we can resume at the same position when returning
			if( previousSlide && previousSlide.parentNode && previousSlide.parentNode.classList.contains( 'stack' ) ) {
			setPreviousVerticalIndex( previousSlide.parentNode, indexv );
			}

			// Remember the state before this slide
			var stateBefore = state.concat();

			// Reset the state array
			state.length = 0;

			var indexhBefore = indexh \|\| 0,
			indexvBefore = indexv \|\| 0;

			// Activate and transition to the new slide
			indexh = updateSlides( HORIZONTAL_SLIDES_SELECTOR, h === undefined ? indexh : h );
			indexv = updateSlides( VERTICAL_SLIDES_SELECTOR, v === undefined ? indexv : v );

			// Update the visibility of slides now that the indices have changed
			updateSlidesVisibility();

			layout();

			// Apply the new state
			stateLoop: for( var i = 0, len = state.length; i < len; i++ ) {
			// Check if this state existed on the previous slide. If it
			// did, we will avoid adding it repeatedly
			for( var j = 0; j < stateBefore.length; j++ ) {
			if( stateBefore[j] === state[i] ) {
			stateBefore.splice( j, 1 );
			continue stateLoop;
			}
			}

			document.documentElement.classList.add( state[i] );

			// Dispatch custom event matching the state's name
			dispatchEvent( state[i] );
			}

			// Clean up the remains of the previous state
			while( stateBefore.length ) {
			document.documentElement.classList.remove( stateBefore.pop() );
			}

			// Update the overview if it's currently active
			if( isOverview() ) {
			updateOverview();
			}

			// Find the current horizontal slide and any possible vertical slides
			// within it
			var currentHorizontalSlide = horizontalSlides[ indexh ],
			currentVerticalSlides = currentHorizontalSlide.querySelectorAll( 'section' );

			// Store references to the previous and current slides
			currentSlide = currentVerticalSlides[ indexv ] \|\| currentHorizontalSlide;

			// Show fragment, if specified
			if( typeof f !== 'undefined' ) {
			navigateFragment( f );
			}

			// Dispatch an event if the slide changed
			var slideChanged = ( indexh !== indexhBefore \|\| indexv !== indexvBefore );
			if( slideChanged ) {
			dispatchEvent( 'slidechanged', {
			'indexh': indexh,
			'indexv': indexv,
			'previousSlide': previousSlide,
			'currentSlide': currentSlide,
			'origin': o
			} );
			}
			else {
			// Ensure that the previous slide is never the same as the current
			previousSlide = null;
			}

			// Solves an edge case where the previous slide maintains the
			// 'present' class when navigating between adjacent vertical
			// stacks
			if( previousSlide ) {
			previousSlide.classList.remove( 'present' );
			previousSlide.setAttribute( 'aria-hidden', 'true' );

			// Reset all slides upon navigate to home
			// Issue: #285
			if ( dom.wrapper.querySelector( HOME_SLIDE_SELECTOR ).classList.contains( 'present' ) ) {
			// Launch async task
			setTimeout( function () {
			var slides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.stack') ), i;
			for( i in slides ) {
			if( slides[i] ) {
			// Reset stack
			setPreviousVerticalIndex( slides[i], 0 );
			}
			}
			}, 0 );
			}
			}

			// Handle embedded content
			if( slideChanged \|\| !previousSlide ) {
			stopEmbeddedContent( previousSlide );
			startEmbeddedContent( currentSlide );
			}

			// Announce the current slide contents, for screen readers
			dom.statusDiv.textContent = getStatusText( currentSlide );

			updateControls();
			updateProgress();
			updateBackground();
			updateParallax();
			updateSlideNumber();
			updateNotes();

			// Update the URL hash
			writeURL();

			cueAutoSlide();

			}

			/**
			* Syncs the presentation with the current DOM. Useful
			* when new slides or control elements are added or when
			* the configuration has changed.
			*/
			function sync() {

			// Subscribe to input
			removeEventListeners();
			addEventListeners();

			// Force a layout to make sure the current config is accounted for
			layout();

			// Reflect the current autoSlide value
			autoSlide = config.autoSlide;

			// Start auto-sliding if it's enabled
			cueAutoSlide();

			// Re-create the slide backgrounds
			createBackgrounds();

			// Write the current hash to the URL
			writeURL();

			sortAllFragments();

			updateControls();
			updateProgress();
			updateSlideNumber();
			updateSlidesVisibility();
			updateBackground( true );
			updateNotes();

			formatEmbeddedContent();

			// Start or stop embedded content depending on global config
			if( config.autoPlayMedia === false ) {
			stopEmbeddedContent( currentSlide );
			}
			else {
			startEmbeddedContent( currentSlide );
			}

			if( isOverview() ) {
			layoutOverview();
			}

			}

			/**
			* Resets all vertical slides so that only the first
			* is visible.
			*/
			function resetVerticalSlides() {

			var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
			horizontalSlides.forEach( function( horizontalSlide ) {

			var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) );
			verticalSlides.forEach( function( verticalSlide, y ) {

			if( y > 0 ) {
			verticalSlide.classList.remove( 'present' );
			verticalSlide.classList.remove( 'past' );
			verticalSlide.classList.add( 'future' );
			verticalSlide.setAttribute( 'aria-hidden', 'true' );
			}

			} );

			} );

			}

			/**
			* Sorts and formats all of fragments in the
			* presentation.
			*/
			function sortAllFragments() {

			var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
			horizontalSlides.forEach( function( horizontalSlide ) {

			var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) );
			verticalSlides.forEach( function( verticalSlide, y ) {

			sortFragments( verticalSlide.querySelectorAll( '.fragment' ) );

			} );

			if( verticalSlides.length === 0 ) sortFragments( horizontalSlide.querySelectorAll( '.fragment' ) );

			} );

			}

			/**
			* Randomly shuffles all slides in the deck.
			*/
			function shuffle() {

			var slides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );

			slides.forEach( function( slide ) {

			// Insert this slide next to another random slide. This may
			// cause the slide to insert before itself but that's fine.
			dom.slides.insertBefore( slide, slides[ Math.floor( Math.random() * slides.length ) ] );

			} );

			}

			/**
			* Updates one dimension of slides by showing the slide
			* with the specified index.
			*
			* @param {string} selector A CSS selector that will fetch
			* the group of slides we are working with
			* @param {number} index The index of the slide that should be
			* shown
			*
			* @return {number} The index of the slide that is now shown,
			* might differ from the passed in index if it was out of
			* bounds.
			*/
			function updateSlides( selector, index ) {

			// Select all slides and convert the NodeList result to
			// an array
			var slides = toArray( dom.wrapper.querySelectorAll( selector ) ),
			slidesLength = slides.length;

			var printMode = isPrintingPDF();

			if( slidesLength ) {

			// Should the index loop?
			if( config.loop ) {
			index %= slidesLength;

			if( index < 0 ) {
			index = slidesLength + index;
			}
			}

			// Enforce max and minimum index bounds
			index = Math.max( Math.min( index, slidesLength - 1 ), 0 );

			for( var i = 0; i < slidesLength; i++ ) {
			var element = slides[i];

			var reverse = config.rtl && !isVerticalSlide( element );

			element.classList.remove( 'past' );
			element.classList.remove( 'present' );
			element.classList.remove( 'future' );

			// http://www.w3.org/html/wg/drafts/html/master/editing.html#the-hidden-attribute
			element.setAttribute( 'hidden', '' );
			element.setAttribute( 'aria-hidden', 'true' );

			// If this element contains vertical slides
			if( element.querySelector( 'section' ) ) {
			element.classList.add( 'stack' );
			}

			// If we're printing static slides, all slides are "present"
			if( printMode ) {
			element.classList.add( 'present' );
			continue;
			}

			if( i < index ) {
			// Any element previous to index is given the 'past' class
			element.classList.add( reverse ? 'future' : 'past' );

			if( config.fragments ) {
			var pastFragments = toArray( element.querySelectorAll( '.fragment' ) );

			// Show all fragments on prior slides
			while( pastFragments.length ) {
			var pastFragment = pastFragments.pop();
			pastFragment.classList.add( 'visible' );
			pastFragment.classList.remove( 'current-fragment' );
			}
			}
			}
			else if( i > index ) {
			// Any element subsequent to index is given the 'future' class
			element.classList.add( reverse ? 'past' : 'future' );

			if( config.fragments ) {
			var futureFragments = toArray( element.querySelectorAll( '.fragment.visible' ) );

			// No fragments in future slides should be visible ahead of time
			while( futureFragments.length ) {
			var futureFragment = futureFragments.pop();
			futureFragment.classList.remove( 'visible' );
			futureFragment.classList.remove( 'current-fragment' );
			}
			}
			}
			}

			// Mark the current slide as present
			slides[index].classList.add( 'present' );
			slides[index].removeAttribute( 'hidden' );
			slides[index].removeAttribute( 'aria-hidden' );

			// If this slide has a state associated with it, add it
			// onto the current state of the deck
			var slideState = slides[index].getAttribute( 'data-state' );
			if( slideState ) {
			state = state.concat( slideState.split( ' ' ) );
			}

			}
			else {
			// Since there are no slides we can't be anywhere beyond the
			// zeroth index
			index = 0;
			}

			return index;

			}

			/**
			* Optimization method; hide all slides that are far away
			* from the present slide.
			*/
			function updateSlidesVisibility() {

			// Select all slides and convert the NodeList result to
			// an array
			var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ),
			horizontalSlidesLength = horizontalSlides.length,
			distanceX,
			distanceY;

			if( horizontalSlidesLength && typeof indexh !== 'undefined' ) {

			// The number of steps away from the present slide that will
			// be visible
			var viewDistance = isOverview() ? 10 : config.viewDistance;

			// Limit view distance on weaker devices
			if( isMobileDevice ) {
			viewDistance = isOverview() ? 6 : 2;
			}

			// All slides need to be visible when exporting to PDF
			if( isPrintingPDF() ) {
			viewDistance = Number.MAX_VALUE;
			}

			for( var x = 0; x < horizontalSlidesLength; x++ ) {
			var horizontalSlide = horizontalSlides[x];

			var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) ),
			verticalSlidesLength = verticalSlides.length;

			// Determine how far away this slide is from the present
			distanceX = Math.abs( ( indexh \|\| 0 ) - x ) \|\| 0;

			// If the presentation is looped, distance should measure
			// 1 between the first and last slides
			if( config.loop ) {
			distanceX = Math.abs( ( ( indexh \|\| 0 ) - x ) % ( horizontalSlidesLength - viewDistance ) ) \|\| 0;
			}

			// Show the horizontal slide if it's within the view distance
			if( distanceX < viewDistance ) {
			showSlide( horizontalSlide );
			}
			else {
			hideSlide( horizontalSlide );
			}

			if( verticalSlidesLength ) {

			var oy = getPreviousVerticalIndex( horizontalSlide );

			for( var y = 0; y < verticalSlidesLength; y++ ) {
			var verticalSlide = verticalSlides[y];

			distanceY = x === ( indexh \|\| 0 ) ? Math.abs( ( indexv \|\| 0 ) - y ) : Math.abs( y - oy );

			if( distanceX + distanceY < viewDistance ) {
			showSlide( verticalSlide );
			}
			else {
			hideSlide( verticalSlide );
			}
			}

			}
			}

			}

			}

			/**
			* Pick up notes from the current slide and display them
			* to the viewer.
			*
			* @see {@link config.showNotes}
			*/
			function updateNotes() {

			if( config.showNotes && dom.speakerNotes && currentSlide && !isPrintingPDF() ) {

			dom.speakerNotes.innerHTML = getSlideNotes() \|\| '';

			}

			}

			/**
			* Updates the progress bar to reflect the current slide.
			*/
			function updateProgress() {

			// Update progress if enabled
			if( config.progress && dom.progressbar ) {

			dom.progressbar.style.width = getProgress() * dom.wrapper.offsetWidth + 'px';

			}

			}

			/**
			* Updates the slide number div to reflect the current slide.
			*
			* The following slide number formats are available:
			* "h.v": horizontal . vertical slide number (default)
			* "h/v": horizontal / vertical slide number
			* "c": flattened slide number
			* "c/t": flattened slide number / total slides
			*/
			function updateSlideNumber() {

			// Update slide number if enabled
			if( config.slideNumber && dom.slideNumber ) {

			var value = [];
			var format = 'h.v';

			// Check if a custom number format is available
			if( typeof config.slideNumber === 'string' ) {
			format = config.slideNumber;
			}

			switch( format ) {
			case 'c':
			value.push( getSlidePastCount() + 1 );
			break;
			case 'c/t':
			value.push( getSlidePastCount() + 1, '/', getTotalSlides() );
			break;
			case 'h/v':
			value.push( indexh + 1 );
			if( isVerticalSlide() ) value.push( '/', indexv + 1 );
			break;
			default:
			value.push( indexh + 1 );
			if( isVerticalSlide() ) value.push( '.', indexv + 1 );
			}

			dom.slideNumber.innerHTML = formatSlideNumber( value[0], value[1], value[2] );
			}

			}

			/**
			* Applies HTML formatting to a slide number before it's
			* written to the DOM.
			*
			* @param {number} a Current slide
			* @param {string} delimiter Character to separate slide numbers
			* @param {(number\|*)} b Total slides
			* @return {string} HTML string fragment
			*/
			function formatSlideNumber( a, delimiter, b ) {

			if( typeof b === 'number' && !isNaN( b ) ) {
			return '<span class="slide-number-a">'+ a +'</span>' +
			'<span class="slide-number-delimiter">'+ delimiter +'</span>' +
			'<span class="slide-number-b">'+ b +'</span>';
			}
			else {
			return '<span class="slide-number-a">'+ a +'</span>';
			}

			}

			/**
			* Updates the state of all control/navigation arrows.
			*/
			function updateControls() {

			var routes = availableRoutes();
			var fragments = availableFragments();

			// Remove the 'enabled' class from all directions
			dom.controlsLeft.concat( dom.controlsRight )
			.concat( dom.controlsUp )
			.concat( dom.controlsDown )
			.concat( dom.controlsPrev )
			.concat( dom.controlsNext ).forEach( function( node ) {
			node.classList.remove( 'enabled' );
			node.classList.remove( 'fragmented' );

			// Set 'disabled' attribute on all directions
			node.setAttribute( 'disabled', 'disabled' );
			} );

			// Add the 'enabled' class to the available routes; remove 'disabled' attribute to enable buttons
			if( routes.left ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute( 'disabled' ); } );
			if( routes.right ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute( 'disabled' ); } );
			if( routes.up ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute( 'disabled' ); } );
			if( routes.down ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute( 'disabled' ); } );

			// Prev/next buttons
			if( routes.left \|\| routes.up ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute( 'disabled' ); } );
			if( routes.right \|\| routes.down ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'enabled' ); el.removeAttribute( 'disabled' ); } );

			// Highlight fragment directions
			if( currentSlide ) {

			// Always apply fragment decorator to prev/next buttons
			if( fragments.prev ) dom.controlsPrev.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
			if( fragments.next ) dom.controlsNext.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );

			// Apply fragment decorators to directional buttons based on
			// what slide axis they are in
			if( isVerticalSlide( currentSlide ) ) {
			if( fragments.prev ) dom.controlsUp.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
			if( fragments.next ) dom.controlsDown.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
			}
			else {
			if( fragments.prev ) dom.controlsLeft.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
			if( fragments.next ) dom.controlsRight.forEach( function( el ) { el.classList.add( 'fragmented', 'enabled' ); el.removeAttribute( 'disabled' ); } );
			}

			}

			}

			/**
			* Updates the background elements to reflect the current
			* slide.
			*
			* @param {boolean} includeAll If true, the backgrounds of
			* all vertical slides (not just the present) will be updated.
			*/
			function updateBackground( includeAll ) {

			var currentBackground = null;

			// Reverse past/future classes when in RTL mode
			var horizontalPast = config.rtl ? 'future' : 'past',
			horizontalFuture = config.rtl ? 'past' : 'future';

			// Update the classes of all backgrounds to match the
			// states of their slides (past/present/future)
			toArray( dom.background.childNodes ).forEach( function( backgroundh, h ) {

			backgroundh.classList.remove( 'past' );
			backgroundh.classList.remove( 'present' );
			backgroundh.classList.remove( 'future' );

			if( h < indexh ) {
			backgroundh.classList.add( horizontalPast );
			}
			else if ( h > indexh ) {
			backgroundh.classList.add( horizontalFuture );
			}
			else {
			backgroundh.classList.add( 'present' );

			// Store a reference to the current background element
			currentBackground = backgroundh;
			}

			if( includeAll \|\| h === indexh ) {
			toArray( backgroundh.querySelectorAll( '.slide-background' ) ).forEach( function( backgroundv, v ) {

			backgroundv.classList.remove( 'past' );
			backgroundv.classList.remove( 'present' );
			backgroundv.classList.remove( 'future' );

			if( v < indexv ) {
			backgroundv.classList.add( 'past' );
			}
			else if ( v > indexv ) {
			backgroundv.classList.add( 'future' );
			}
			else {
			backgroundv.classList.add( 'present' );

			// Only if this is the present horizontal and vertical slide
			if( h === indexh ) currentBackground = backgroundv;
			}

			} );
			}

			} );

			// Stop content inside of previous backgrounds
			if( previousBackground ) {

			stopEmbeddedContent( previousBackground );

			}

			// Start content in the current background
			if( currentBackground ) {

			startEmbeddedContent( currentBackground );

			var backgroundImageURL = currentBackground.style.backgroundImage \|\| '';

			// Restart GIFs (doesn't work in Firefox)
			if( /\.gif/i.test( backgroundImageURL ) ) {
			currentBackground.style.backgroundImage = '';
			window.getComputedStyle( currentBackground ).opacity;
			currentBackground.style.backgroundImage = backgroundImageURL;
			}

			// Don't transition between identical backgrounds. This
			// prevents unwanted flicker.
			var previousBackgroundHash = previousBackground ? previousBackground.getAttribute( 'data-background-hash' ) : null;
			var currentBackgroundHash = currentBackground.getAttribute( 'data-background-hash' );
			if( currentBackgroundHash && currentBackgroundHash === previousBackgroundHash && currentBackground !== previousBackground ) {
			dom.background.classList.add( 'no-transition' );
			}

			previousBackground = currentBackground;

			}

			// If there's a background brightness flag for this slide,
			// bubble it to the .reveal container
			if( currentSlide ) {
			[ 'has-light-background', 'has-dark-background' ].forEach( function( classToBubble ) {
			if( currentSlide.classList.contains( classToBubble ) ) {
			dom.wrapper.classList.add( classToBubble );
			}
			else {
			dom.wrapper.classList.remove( classToBubble );
			}
			} );
			}

			// Allow the first background to apply without transition
			setTimeout( function() {
			dom.background.classList.remove( 'no-transition' );
			}, 1 );

			}

			/**
			* Updates the position of the parallax background based
			* on the current slide index.
			*/
			function updateParallax() {

			if( config.parallaxBackgroundImage ) {

			var horizontalSlides = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ),
			verticalSlides = dom.wrapper.querySelectorAll( VERTICAL_SLIDES_SELECTOR );

			var backgroundSize = dom.background.style.backgroundSize.split( ' ' ),
			backgroundWidth, backgroundHeight;

			if( backgroundSize.length === 1 ) {
			backgroundWidth = backgroundHeight = parseInt( backgroundSize[0], 10 );
			}
			else {
			backgroundWidth = parseInt( backgroundSize[0], 10 );
			backgroundHeight = parseInt( backgroundSize[1], 10 );
			}

			var slideWidth = dom.background.offsetWidth,
			horizontalSlideCount = horizontalSlides.length,
			horizontalOffsetMultiplier,
			horizontalOffset;

			if( typeof config.parallaxBackgroundHorizontal === 'number' ) {
			horizontalOffsetMultiplier = config.parallaxBackgroundHorizontal;
			}
			else {
			horizontalOffsetMultiplier = horizontalSlideCount > 1 ? ( backgroundWidth - slideWidth ) / ( horizontalSlideCount-1 ) : 0;
			}

			horizontalOffset = horizontalOffsetMultiplier * indexh * -1;

			var slideHeight = dom.background.offsetHeight,
			verticalSlideCount = verticalSlides.length,
			verticalOffsetMultiplier,
			verticalOffset;

			if( typeof config.parallaxBackgroundVertical === 'number' ) {
			verticalOffsetMultiplier = config.parallaxBackgroundVertical;
			}
			else {
			verticalOffsetMultiplier = ( backgroundHeight - slideHeight ) / ( verticalSlideCount-1 );
			}

			verticalOffset = verticalSlideCount > 0 ? verticalOffsetMultiplier * indexv : 0;

			dom.background.style.backgroundPosition = horizontalOffset + 'px ' + -verticalOffset + 'px';

			}

			}

			/**
			* Called when the given slide is within the configured view
			* distance. Shows the slide element and loads any content
			* that is set to load lazily (data-src).
			*
			* @param {HTMLElement} slide Slide to show
			*/
			/**
			* Called when the given slide is within the configured view
			* distance. Shows the slide element and loads any content
			* that is set to load lazily (data-src).
			*
			* @param {HTMLElement} slide Slide to show
			*/
			function showSlide( slide ) {

			// Show the slide element
			slide.style.display = config.display;

			// Media elements with data-src attributes
			toArray( slide.querySelectorAll( 'img[data-src], video[data-src], audio[data-src]' ) ).forEach( function( element ) {
			element.setAttribute( 'src', element.getAttribute( 'data-src' ) );
			element.removeAttribute( 'data-src' );
			} );

			// Media elements with <source> children
			toArray( slide.querySelectorAll( 'video, audio' ) ).forEach( function( media ) {
			var sources = 0;

			toArray( media.querySelectorAll( 'source[data-src]' ) ).forEach( function( source ) {
			source.setAttribute( 'src', source.getAttribute( 'data-src' ) );
			source.removeAttribute( 'data-src' );
			sources += 1;
			} );

			// If we rewrote sources for this video/audio element, we need
			// to manually tell it to load from its new origin
			if( sources > 0 ) {
			media.load();
			}
			} );


			// Show the corresponding background element
			var indices = getIndices( slide );
			var background = getSlideBackground( indices.h, indices.v );
			if( background ) {
			background.style.display = 'block';

			// If the background contains media, load it
			if( background.hasAttribute( 'data-loaded' ) === false ) {
			background.setAttribute( 'data-loaded', 'true' );

			var backgroundImage = slide.getAttribute( 'data-background-image' ),
			backgroundVideo = slide.getAttribute( 'data-background-video' ),
			backgroundVideoLoop = slide.hasAttribute( 'data-background-video-loop' ),
			backgroundVideoMuted = slide.hasAttribute( 'data-background-video-muted' ),
			backgroundIframe = slide.getAttribute( 'data-background-iframe' );

			// Images
			if( backgroundImage ) {
			background.style.backgroundImage = 'url('+ backgroundImage +')';
			}
			// Videos
			else if ( backgroundVideo && !isSpeakerNotes() ) {
			var video = document.createElement( 'video' );

			if( backgroundVideoLoop ) {
			video.setAttribute( 'loop', '' );
			}

			if( backgroundVideoMuted ) {
			video.muted = true;
			}

			// Inline video playback works (at least in Mobile Safari) as
			// long as the video is muted and the `playsinline` attribute is
			// present
			if( isMobileDevice ) {
			video.muted = true;
			video.autoplay = true;
			video.setAttribute( 'playsinline', '' );
			}

			// Support comma separated lists of video sources
			backgroundVideo.split( ',' ).forEach( function( source ) {
			video.innerHTML += '<source src="'+ source +'">';
			} );

			background.appendChild( video );
			}
			// Iframes
			else if( backgroundIframe ) {
			var iframe = document.createElement( 'iframe' );
			iframe.setAttribute( 'allowfullscreen', '' );
			iframe.setAttribute( 'mozallowfullscreen', '' );
			iframe.setAttribute( 'webkitallowfullscreen', '' );

			// Only load autoplaying content when the slide is shown to
			// avoid having it play in the background
			if( /autoplay=(1\|true\|yes)/gi.test( backgroundIframe ) ) {
			iframe.setAttribute( 'data-src', backgroundIframe );
			}
			else {
			iframe.setAttribute( 'src', backgroundIframe );
			}

			iframe.style.width = '100%';
			iframe.style.height = '100%';
			iframe.style.maxHeight = '100%';
			iframe.style.maxWidth = '100%';

			background.appendChild( iframe );
			}
			}

			}

			}

			/**
			* Called when the given slide is moved outside of the
			* configured view distance.
			*
			* @param {HTMLElement} slide
			*/
			function hideSlide( slide ) {

			// Hide the slide element
			slide.style.display = 'none';

			// Hide the corresponding background element
			var indices = getIndices( slide );
			var background = getSlideBackground( indices.h, indices.v );
			if( background ) {
			background.style.display = 'none';
			}

			}

			/**
			* Determine what available routes there are for navigation.
			*
			* @return {{left: boolean, right: boolean, up: boolean, down: boolean}}
			*/
			function availableRoutes() {

			var horizontalSlides = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ),
			verticalSlides = dom.wrapper.querySelectorAll( VERTICAL_SLIDES_SELECTOR );

			var routes = {
			left: indexh > 0 \|\| config.loop,
			right: indexh < horizontalSlides.length - 1 \|\| config.loop,
			up: indexv > 0,
			down: indexv < verticalSlides.length - 1
			};

			// reverse horizontal controls for rtl
			if( config.rtl ) {
			var left = routes.left;
			routes.left = routes.right;
			routes.right = left;
			}

			return routes;

			}

			/**
			* Returns an object describing the available fragment
			* directions.
			*
			* @return {{prev: boolean, next: boolean}}
			*/
			function availableFragments() {

			if( currentSlide && config.fragments ) {
			var fragments = currentSlide.querySelectorAll( '.fragment' );
			var hiddenFragments = currentSlide.querySelectorAll( '.fragment:not(.visible)' );

			return {
			prev: fragments.length - hiddenFragments.length > 0,
			next: !!hiddenFragments.length
			};
			}
			else {
			return { prev: false, next: false };
			}

			}

			/**
			* Enforces origin-specific format rules for embedded media.
			*/
			function formatEmbeddedContent() {

			var _appendParamToIframeSource = function( sourceAttribute, sourceURL, param ) {
			toArray( dom.slides.querySelectorAll( 'iframe['+ sourceAttribute +'*="'+ sourceURL +'"]' ) ).forEach( function( el ) {
			var src = el.getAttribute( sourceAttribute );
			if( src && src.indexOf( param ) === -1 ) {
			el.setAttribute( sourceAttribute, src + ( !/\?/.test( src ) ? '?' : '&' ) + param );
			}
			});
			};

			// YouTube frames must include "?enablejsapi=1"
			_appendParamToIframeSource( 'src', 'youtube.com/embed/', 'enablejsapi=1' );
			_appendParamToIframeSource( 'data-src', 'youtube.com/embed/', 'enablejsapi=1' );

			// Vimeo frames must include "?api=1"
			_appendParamToIframeSource( 'src', 'player.vimeo.com/', 'api=1' );
			_appendParamToIframeSource( 'data-src', 'player.vimeo.com/', 'api=1' );

			}

			/**
			* Start playback of any embedded content inside of
			* the given element.
			*
			* @param {HTMLElement} element
			*/
			function startEmbeddedContent( element ) {

			if( element && !isSpeakerNotes() ) {

			// Restart GIFs
			toArray( element.querySelectorAll( 'img[src$=".gif"]' ) ).forEach( function( el ) {
			// Setting the same unchanged source like this was confirmed
			// to work in Chrome, FF & Safari
			el.setAttribute( 'src', el.getAttribute( 'src' ) );
			} );

			// HTML5 media elements
			toArray( element.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
			if( closestParent( el, '.fragment' ) && !closestParent( el, '.fragment.visible' ) ) {
			return;
			}

			// Prefer an explicit global autoplay setting
			var autoplay = config.autoPlayMedia;

			// If no global setting is available, fall back on the element's
			// own autoplay setting
			if( typeof autoplay !== 'boolean' ) {
			autoplay = el.hasAttribute( 'data-autoplay' ) \|\| !!closestParent( el, '.slide-background' );
			}

			if( autoplay && typeof el.play === 'function' ) {

			if( el.readyState > 1 ) {
			startEmbeddedMedia( { target: el } );
			}
			else {
			el.removeEventListener( 'loadeddata', startEmbeddedMedia ); // remove first to avoid dupes
			el.addEventListener( 'loadeddata', startEmbeddedMedia );
			}

			}
			} );

			// Normal iframes
			toArray( element.querySelectorAll( 'iframe[src]' ) ).forEach( function( el ) {
			if( closestParent( el, '.fragment' ) && !closestParent( el, '.fragment.visible' ) ) {
			return;
			}

			startEmbeddedIframe( { target: el } );
			} );

			// Lazy loading iframes
			toArray( element.querySelectorAll( 'iframe[data-src]' ) ).forEach( function( el ) {
			if( closestParent( el, '.fragment' ) && !closestParent( el, '.fragment.visible' ) ) {
			return;
			}

			if( el.getAttribute( 'src' ) !== el.getAttribute( 'data-src' ) ) {
			el.removeEventListener( 'load', startEmbeddedIframe ); // remove first to avoid dupes
			el.addEventListener( 'load', startEmbeddedIframe );
			el.setAttribute( 'src', el.getAttribute( 'data-src' ) );
			}
			} );

			}

			}

			/**
			* Starts playing an embedded video/audio element after
			* it has finished loading.
			*
			* @param {object} event
			*/
			function startEmbeddedMedia( event ) {

			var isAttachedToDOM = !!closestParent( event.target, 'html' ),
			isVisible = !!closestParent( event.target, '.present' );

			if( isAttachedToDOM && isVisible ) {
			event.target.currentTime = 0;
			event.target.play();
			}

			event.target.removeEventListener( 'loadeddata', startEmbeddedMedia );

			}

			/**
			* "Starts" the content of an embedded iframe using the
			* postMessage API.
			*
			* @param {object} event
			*/
			function startEmbeddedIframe( event ) {

			var iframe = event.target;

			if( iframe && iframe.contentWindow ) {

			var isAttachedToDOM = !!closestParent( event.target, 'html' ),
			isVisible = !!closestParent( event.target, '.present' );

			if( isAttachedToDOM && isVisible ) {

			// Prefer an explicit global autoplay setting
			var autoplay = config.autoPlayMedia;

			// If no global setting is available, fall back on the element's
			// own autoplay setting
			if( typeof autoplay !== 'boolean' ) {
			autoplay = iframe.hasAttribute( 'data-autoplay' ) \|\| !!closestParent( iframe, '.slide-background' );
			}

			// YouTube postMessage API
			if( /youtube\.com\/embed\//.test( iframe.getAttribute( 'src' ) ) && autoplay ) {
			iframe.contentWindow.postMessage( '{"event":"command","func":"playVideo","args":""}', '*' );
			}
			// Vimeo postMessage API
			else if( /player\.vimeo\.com\//.test( iframe.getAttribute( 'src' ) ) && autoplay ) {
			iframe.contentWindow.postMessage( '{"method":"play"}', '*' );
			}
			// Generic postMessage API
			else {
			iframe.contentWindow.postMessage( 'slide:start', '*' );
			}

			}

			}

			}

			/**
			* Stop playback of any embedded content inside of
			* the targeted slide.
			*
			* @param {HTMLElement} element
			*/
			function stopEmbeddedContent( element ) {

			if( element && element.parentNode ) {
			// HTML5 media elements
			toArray( element.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
			if( !el.hasAttribute( 'data-ignore' ) && typeof el.pause === 'function' ) {
			el.setAttribute('data-paused-by-reveal', '');
			el.pause();
			}
			} );

			// Generic postMessage API for non-lazy loaded iframes
			toArray( element.querySelectorAll( 'iframe' ) ).forEach( function( el ) {
			if( el.contentWindow ) el.contentWindow.postMessage( 'slide:stop', '*' );
			el.removeEventListener( 'load', startEmbeddedIframe );
			});

			// YouTube postMessage API
			toArray( element.querySelectorAll( 'iframe[src*="youtube.com/embed/"]' ) ).forEach( function( el ) {
			if( !el.hasAttribute( 'data-ignore' ) && el.contentWindow && typeof el.contentWindow.postMessage === 'function' ) {
			el.contentWindow.postMessage( '{"event":"command","func":"pauseVideo","args":""}', '*' );
			}
			});

			// Vimeo postMessage API
			toArray( element.querySelectorAll( 'iframe[src*="player.vimeo.com/"]' ) ).forEach( function( el ) {
			if( !el.hasAttribute( 'data-ignore' ) && el.contentWindow && typeof el.contentWindow.postMessage === 'function' ) {
			el.contentWindow.postMessage( '{"method":"pause"}', '*' );
			}
			});

			// Lazy loading iframes
			toArray( element.querySelectorAll( 'iframe[data-src]' ) ).forEach( function( el ) {
			// Only removing the src doesn't actually unload the frame
			// in all browsers (Firefox) so we set it to blank first
			el.setAttribute( 'src', 'about:blank' );
			el.removeAttribute( 'src' );
			} );
			}

			}

			/**
			* Returns the number of past slides. This can be used as a global
			* flattened index for slides.
			*
			* @return {number} Past slide count
			*/
			function getSlidePastCount() {

			var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );

			// The number of past slides
			var pastCount = 0;

			// Step through all slides and count the past ones
			mainLoop: for( var i = 0; i < horizontalSlides.length; i++ ) {

			var horizontalSlide = horizontalSlides[i];
			var verticalSlides = toArray( horizontalSlide.querySelectorAll( 'section' ) );

			for( var j = 0; j < verticalSlides.length; j++ ) {

			// Stop as soon as we arrive at the present
			if( verticalSlides[j].classList.contains( 'present' ) ) {
			break mainLoop;
			}

			pastCount++;

			}

			// Stop as soon as we arrive at the present
			if( horizontalSlide.classList.contains( 'present' ) ) {
			break;
			}

			// Don't count the wrapping section for vertical slides
			if( horizontalSlide.classList.contains( 'stack' ) === false ) {
			pastCount++;
			}

			}

			return pastCount;

			}

			/**
			* Returns a value ranging from 0-1 that represents
			* how far into the presentation we have navigated.
			*
			* @return {number}
			*/
			function getProgress() {

			// The number of past and total slides
			var totalCount = getTotalSlides();
			var pastCount = getSlidePastCount();

			if( currentSlide ) {

			var allFragments = currentSlide.querySelectorAll( '.fragment' );

			// If there are fragments in the current slide those should be
			// accounted for in the progress.
			if( allFragments.length > 0 ) {
			var visibleFragments = currentSlide.querySelectorAll( '.fragment.visible' );

			// This value represents how big a portion of the slide progress
			// that is made up by its fragments (0-1)
			var fragmentWeight = 0.9;

			// Add fragment progress to the past slide count
			pastCount += ( visibleFragments.length / allFragments.length ) * fragmentWeight;
			}

			}

			return pastCount / ( totalCount - 1 );

			}

			/**
			* Checks if this presentation is running inside of the
			* speaker notes window.
			*
			* @return {boolean}
			*/
			function isSpeakerNotes() {

			return !!window.location.search.match( /receiver/gi );

			}

			/**
			* Reads the current URL (hash) and navigates accordingly.
			*/
			function readURL() {

			var hash = window.location.hash;

			// Attempt to parse the hash as either an index or name
			var bits = hash.slice( 2 ).split( '/' ),
			name = hash.replace( /#\|\//gi, '' );

			// If the first bit is invalid and there is a name we can
			// assume that this is a named link
			if( isNaN( parseInt( bits[0], 10 ) ) && name.length ) {
			var element;

			// Ensure the named link is a valid HTML ID attribute
			if( /^[a-zA-Z][\w:.-]*$/.test( name ) ) {
			// Find the slide with the specified ID
			element = document.getElementById( name );
			}

			if( element ) {
			// Find the position of the named slide and navigate to it
			var indices = Reveal.getIndices( element );
			slide( indices.h, indices.v );
			}
			// If the slide doesn't exist, navigate to the current slide
			else {
			slide( indexh \|\| 0, indexv \|\| 0 );
			}
			}
			else {
			// Read the index components of the hash
			var h = parseInt( bits[0], 10 ) \|\| 0,
			v = parseInt( bits[1], 10 ) \|\| 0;

			if( h !== indexh \|\| v !== indexv ) {
			slide( h, v );
			}
			}

			}

			/**
			* Updates the page URL (hash) to reflect the current
			* state.
			*
			* @param {number} delay The time in ms to wait before
			* writing the hash
			*/
			function writeURL( delay ) {

			if( config.history ) {

			// Make sure there's never more than one timeout running
			clearTimeout( writeURLTimeout );

			// If a delay is specified, timeout this call
			if( typeof delay === 'number' ) {
			writeURLTimeout = setTimeout( writeURL, delay );
			}
			else if( currentSlide ) {
			var url = '/';

			// Attempt to create a named link based on the slide's ID
			var id = currentSlide.getAttribute( 'id' );
			if( id ) {
			id = id.replace( /[^a-zA-Z0-9\-\_\:\.]/g, '' );
			}

			// If the current slide has an ID, use that as a named link
			if( typeof id === 'string' && id.length ) {
			url = '/' + id;
			}
			// Otherwise use the /h/v index
			else {
			if( indexh > 0 \|\| indexv > 0 ) url += indexh;
			if( indexv > 0 ) url += '/' + indexv;
			}

			window.location.hash = url;
			}
			}

			}
			/**
			* Retrieves the h/v location and fragment of the current,
			* or specified, slide.
			*
			* @param {HTMLElement} [slide] If specified, the returned
			* index will be for this slide rather than the currently
			* active one
			*
			* @return {{h: number, v: number, f: number}}
			*/
			function getIndices( slide ) {

			// By default, return the current indices
			var h = indexh,
			v = indexv,
			f;

			// If a slide is specified, return the indices of that slide
			if( slide ) {
			var isVertical = isVerticalSlide( slide );
			var slideh = isVertical ? slide.parentNode : slide;

			// Select all horizontal slides
			var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );

			// Now that we know which the horizontal slide is, get its index
			h = Math.max( horizontalSlides.indexOf( slideh ), 0 );

			// Assume we're not vertical
			v = undefined;

			// If this is a vertical slide, grab the vertical index
			if( isVertical ) {
			v = Math.max( toArray( slide.parentNode.querySelectorAll( 'section' ) ).indexOf( slide ), 0 );
			}
			}

			if( !slide && currentSlide ) {
			var hasFragments = currentSlide.querySelectorAll( '.fragment' ).length > 0;
			if( hasFragments ) {
			var currentFragment = currentSlide.querySelector( '.current-fragment' );
			if( currentFragment && currentFragment.hasAttribute( 'data-fragment-index' ) ) {
			f = parseInt( currentFragment.getAttribute( 'data-fragment-index' ), 10 );
			}
			else {
			f = currentSlide.querySelectorAll( '.fragment.visible' ).length - 1;
			}
			}
			}

			return { h: h, v: v, f: f };

			}

			/**
			* Retrieves all slides in this presentation.
			*/
			function getSlides() {

			return toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ':not(.stack)' ));

			}

			/**
			* Retrieves the total number of slides in this presentation.
			*
			* @return {number}
			*/
			function getTotalSlides() {

			return getSlides().length;

			}

			/**
			* Returns the slide element matching the specified index.
			*
			* @return {HTMLElement}
			*/
			function getSlide( x, y ) {

			var horizontalSlide = dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR )[ x ];
			var verticalSlides = horizontalSlide && horizontalSlide.querySelectorAll( 'section' );

			if( verticalSlides && verticalSlides.length && typeof y === 'number' ) {
			return verticalSlides ? verticalSlides[ y ] : undefined;
			}

			return horizontalSlide;

			}

			/**
			* Returns the background element for the given slide.
			* All slides, even the ones with no background properties
			* defined, have a background element so as long as the
			* index is valid an element will be returned.
			*
			* @param {number} x Horizontal background index
			* @param {number} y Vertical background index
			* @return {(HTMLElement[]\|*)}
			*/
			function getSlideBackground( x, y ) {

			// When printing to PDF the slide backgrounds are nested
			// inside of the slides
			if( isPrintingPDF() ) {
			var slide = getSlide( x, y );
			if( slide ) {
			return slide.slideBackgroundElement;
			}

			return undefined;
			}

			var horizontalBackground = dom.wrapper.querySelectorAll( '.backgrounds>.slide-background' )[ x ];
			var verticalBackgrounds = horizontalBackground && horizontalBackground.querySelectorAll( '.slide-background' );

			if( verticalBackgrounds && verticalBackgrounds.length && typeof y === 'number' ) {
			return verticalBackgrounds ? verticalBackgrounds[ y ] : undefined;
			}

			return horizontalBackground;

			}

			/**
			* Retrieves the speaker notes from a slide. Notes can be
			* defined in two ways:
			* 1. As a data-notes attribute on the slide <section>
			* 2. As an <aside class="notes"> inside of the slide
			*
			* @param {HTMLElement} [slide=currentSlide]
			* @return {(string\|null)}
			*/
			function getSlideNotes( slide ) {

			// Default to the current slide
			slide = slide \|\| currentSlide;

			// Notes can be specified via the data-notes attribute...
			if( slide.hasAttribute( 'data-notes' ) ) {
			return slide.getAttribute( 'data-notes' );
			}

			// ... or using an <aside class="notes"> element
			var notesElement = slide.querySelector( 'aside.notes' );
			if( notesElement ) {
			return notesElement.innerHTML;
			}

			return null;

			}

			/**
			* Retrieves the current state of the presentation as
			* an object. This state can then be restored at any
			* time.
			*
			* @return {{indexh: number, indexv: number, indexf: number, paused: boolean, overview: boolean}}
			*/
			function getState() {

			var indices = getIndices();

			return {
			indexh: indices.h,
			indexv: indices.v,
			indexf: indices.f,
			paused: isPaused(),
			overview: isOverview()
			};

			}

			/**
			* Restores the presentation to the given state.
			*
			* @param {object} state As generated by getState()
			* @see {@link getState} generates the parameter `state`
			*/
			function setState( state ) {

			if( typeof state === 'object' ) {
			slide( deserialize( state.indexh ), deserialize( state.indexv ), deserialize( state.indexf ) );

			var pausedFlag = deserialize( state.paused ),
			overviewFlag = deserialize( state.overview );

			if( typeof pausedFlag === 'boolean' && pausedFlag !== isPaused() ) {
			togglePause( pausedFlag );
			}

			if( typeof overviewFlag === 'boolean' && overviewFlag !== isOverview() ) {
			toggleOverview( overviewFlag );
			}
			}

			}

			/**
			* Return a sorted fragments list, ordered by an increasing
			* "data-fragment-index" attribute.
			*
			* Fragments will be revealed in the order that they are returned by
			* this function, so you can use the index attributes to control the
			* order of fragment appearance.
			*
			* To maintain a sensible default fragment order, fragments are presumed
			* to be passed in document order. This function adds a "fragment-index"
			* attribute to each node if such an attribute is not already present,
			* and sets that attribute to an integer value which is the position of
			* the fragment within the fragments list.
			*
			* @param {object[]\|*} fragments
			* @return {object[]} sorted Sorted array of fragments
			*/
			function sortFragments( fragments ) {

			fragments = toArray( fragments );

			var ordered = [],
			unordered = [],
			sorted = [];

			// Group ordered and unordered elements
			fragments.forEach( function( fragment, i ) {
			if( fragment.hasAttribute( 'data-fragment-index' ) ) {
			var index = parseInt( fragment.getAttribute( 'data-fragment-index' ), 10 );

			if( !ordered[index] ) {
			ordered[index] = [];
			}

			ordered[index].push( fragment );
			}
			else {
			unordered.push( [ fragment ] );
			}
			} );

			// Append fragments without explicit indices in their
			// DOM order
			ordered = ordered.concat( unordered );

			// Manually count the index up per group to ensure there
			// are no gaps
			var index = 0;

			// Push all fragments in their sorted order to an array,
			// this flattens the groups
			ordered.forEach( function( group ) {
			group.forEach( function( fragment ) {
			sorted.push( fragment );
			fragment.setAttribute( 'data-fragment-index', index );
			} );

			index ++;
			} );

			return sorted;

			}

			/**
			* Navigate to the specified slide fragment.
			*
			* @param {?number} index The index of the fragment that
			* should be shown, -1 means all are invisible
			* @param {number} offset Integer offset to apply to the
			* fragment index
			*
			* @return {boolean} true if a change was made in any
			* fragments visibility as part of this call
			*/
			function navigateFragment( index, offset ) {

			if( currentSlide && config.fragments ) {

			var fragments = sortFragments( currentSlide.querySelectorAll( '.fragment' ) );
			if( fragments.length ) {

			// If no index is specified, find the current
			if( typeof index !== 'number' ) {
			var lastVisibleFragment = sortFragments( currentSlide.querySelectorAll( '.fragment.visible' ) ).pop();

			if( lastVisibleFragment ) {
			index = parseInt( lastVisibleFragment.getAttribute( 'data-fragment-index' ) \|\| 0, 10 );
			}
			else {
			index = -1;
			}
			}

			// If an offset is specified, apply it to the index
			if( typeof offset === 'number' ) {
			index += offset;
			}

			var fragmentsShown = [],
			fragmentsHidden = [];

			toArray( fragments ).forEach( function( element, i ) {

			if( element.hasAttribute( 'data-fragment-index' ) ) {
			i = parseInt( element.getAttribute( 'data-fragment-index' ), 10 );
			}

			// Visible fragments
			if( i <= index ) {
			if( !element.classList.contains( 'visible' ) ) fragmentsShown.push( element );
			element.classList.add( 'visible' );
			element.classList.remove( 'current-fragment' );

			// Announce the fragments one by one to the Screen Reader
			dom.statusDiv.textContent = getStatusText( element );

			if( i === index ) {
			element.classList.add( 'current-fragment' );
			startEmbeddedContent( element );
			}
			}
			// Hidden fragments
			else {
			if( element.classList.contains( 'visible' ) ) fragmentsHidden.push( element );
			element.classList.remove( 'visible' );
			element.classList.remove( 'current-fragment' );
			}

			} );

			if( fragmentsHidden.length ) {
			dispatchEvent( 'fragmenthidden', { fragment: fragmentsHidden[0], fragments: fragmentsHidden } );
			}

			if( fragmentsShown.length ) {
			dispatchEvent( 'fragmentshown', { fragment: fragmentsShown[0], fragments: fragmentsShown } );
			}

			updateControls();
			updateProgress();

			return !!( fragmentsShown.length \|\| fragmentsHidden.length );

			}

			}

			return false;

			}

			/**
			* Navigate to the next slide fragment.
			*
			* @return {boolean} true if there was a next fragment,
			* false otherwise
			*/
			function nextFragment() {

			return navigateFragment( null, 1 );

			}

			/**
			* Navigate to the previous slide fragment.
			*
			* @return {boolean} true if there was a previous fragment,
			* false otherwise
			*/
			function previousFragment() {

			return navigateFragment( null, -1 );

			}

			/**
			* Cues a new automated slide if enabled in the config.
			*/
			function cueAutoSlide() {

			cancelAutoSlide();

			if( currentSlide ) {

			var fragment = currentSlide.querySelector( '.current-fragment' );

			// When the slide first appears there is no "current" fragment so
			// we look for a data-autoslide timing on the first fragment
			if( !fragment ) fragment = currentSlide.querySelector( '.fragment' );

			var fragmentAutoSlide = fragment ? fragment.getAttribute( 'data-autoslide' ) : null;
			var parentAutoSlide = currentSlide.parentNode ? currentSlide.parentNode.getAttribute( 'data-autoslide' ) : null;
			var slideAutoSlide = currentSlide.getAttribute( 'data-autoslide' );

			// Pick value in the following priority order:
			// 1. Current fragment's data-autoslide
			// 2. Current slide's data-autoslide
			// 3. Parent slide's data-autoslide
			// 4. Global autoSlide setting
			if( fragmentAutoSlide ) {
			autoSlide = parseInt( fragmentAutoSlide, 10 );
			}
			else if( slideAutoSlide ) {
			autoSlide = parseInt( slideAutoSlide, 10 );
			}
			else if( parentAutoSlide ) {
			autoSlide = parseInt( parentAutoSlide, 10 );
			}
			else {
			autoSlide = config.autoSlide;
			}

			// If there are media elements with data-autoplay,
			// automatically set the autoSlide duration to the
			// length of that media. Not applicable if the slide
			// is divided up into fragments.
			// playbackRate is accounted for in the duration.
			if( currentSlide.querySelectorAll( '.fragment' ).length === 0 ) {
			toArray( currentSlide.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
			if( el.hasAttribute( 'data-autoplay' ) ) {
			if( autoSlide && (el.duration * 1000 / el.playbackRate ) > autoSlide ) {
			autoSlide = ( el.duration * 1000 / el.playbackRate ) + 1000;
			}
			}
			} );
			}

			// Cue the next auto-slide if:
			// - There is an autoSlide value
			// - Auto-sliding isn't paused by the user
			// - The presentation isn't paused
			// - The overview isn't active
			// - The presentation isn't over
			if( autoSlide && !autoSlidePaused && !isPaused() && !isOverview() && ( !Reveal.isLastSlide() \|\| availableFragments().next \|\| config.loop === true ) ) {
			autoSlideTimeout = setTimeout( function() {
			typeof config.autoSlideMethod === 'function' ? config.autoSlideMethod() : navigateNext();
			cueAutoSlide();
			}, autoSlide );
			autoSlideStartTime = Date.now();
			}

			if( autoSlidePlayer ) {
			autoSlidePlayer.setPlaying( autoSlideTimeout !== -1 );
			}

			}

			}

			/**
			* Cancels any ongoing request to auto-slide.
			*/
			function cancelAutoSlide() {

			clearTimeout( autoSlideTimeout );
			autoSlideTimeout = -1;

			}

			function pauseAutoSlide() {

			if( autoSlide && !autoSlidePaused ) {
			autoSlidePaused = true;
			dispatchEvent( 'autoslidepaused' );
			clearTimeout( autoSlideTimeout );

			if( autoSlidePlayer ) {
			autoSlidePlayer.setPlaying( false );
			}
			}

			}

			function resumeAutoSlide() {

			if( autoSlide && autoSlidePaused ) {
			autoSlidePaused = false;
			dispatchEvent( 'autoslideresumed' );
			cueAutoSlide();
			}

			}

			function navigateLeft() {

			// Reverse for RTL
			if( config.rtl ) {
			if( ( isOverview() \|\| nextFragment() === false ) && availableRoutes().left ) {
			slide( indexh + 1 );
			}
			}
			// Normal navigation
			else if( ( isOverview() \|\| previousFragment() === false ) && availableRoutes().left ) {
			slide( indexh - 1 );
			}

			}

			function navigateRight() {

			// Reverse for RTL
			if( config.rtl ) {
			if( ( isOverview() \|\| previousFragment() === false ) && availableRoutes().right ) {
			slide( indexh - 1 );
			}
			}
			// Normal navigation
			else if( ( isOverview() \|\| nextFragment() === false ) && availableRoutes().right ) {
			slide( indexh + 1 );
			}

			}

			function navigateUp() {

			// Prioritize hiding fragments
			if( ( isOverview() \|\| previousFragment() === false ) && availableRoutes().up ) {
			slide( indexh, indexv - 1 );
			}

			}

			function navigateDown() {

			// Prioritize revealing fragments
			if( ( isOverview() \|\| nextFragment() === false ) && availableRoutes().down ) {
			slide( indexh, indexv + 1 );
			}

			}

			/**
			* Navigates backwards, prioritized in the following order:
			* 1) Previous fragment
			* 2) Previous vertical slide
			* 3) Previous horizontal slide
			*/
			function navigatePrev() {

			// Prioritize revealing fragments
			if( previousFragment() === false ) {
			if( availableRoutes().up ) {
			navigateUp();
			}
			else {
			// Fetch the previous horizontal slide, if there is one
			var previousSlide;

			if( config.rtl ) {
			previousSlide = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.future' ) ).pop();
			}
			else {
			previousSlide = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR + '.past' ) ).pop();
			}

			if( previousSlide ) {
			var v = ( previousSlide.querySelectorAll( 'section' ).length - 1 ) \|\| undefined;
			var h = indexh - 1;
			slide( h, v );
			}
			}
			}

			}

			/**
			* The reverse of #navigatePrev().
			*/
			function navigateNext() {

			// Prioritize revealing fragments
			if( nextFragment() === false ) {
			if( availableRoutes().down ) {
			navigateDown();
			}
			else if( config.rtl ) {
			navigateLeft();
			}
			else {
			navigateRight();
			}
			}

			}

			/**
			* Checks if the target element prevents the triggering of
			* swipe navigation.
			*/
			function isSwipePrevented( target ) {

			while( target && typeof target.hasAttribute === 'function' ) {
			if( target.hasAttribute( 'data-prevent-swipe' ) ) return true;
			target = target.parentNode;
			}

			return false;

			}


			// --------------------------------------------------------------------//
			// ----------------------------- EVENTS -------------------------------//
			// --------------------------------------------------------------------//

			/**
			* Called by all event handlers that are based on user
			* input.
			*
			* @param {object} [event]
			*/
			function onUserInput( event ) {

			if( config.autoSlideStoppable ) {
			pauseAutoSlide();
			}

			}

			/**
			* Handler for the document level 'keypress' event.
			*
			* @param {object} event
			*/
			function onDocumentKeyPress( event ) {

			// Check if the pressed key is question mark
			if( event.shiftKey && event.charCode === 63 ) {
			toggleHelp();
			}

			}

			/**
			* Handler for the document level 'keydown' event.
			*
			* @param {object} event
			*/
			function onDocumentKeyDown( event ) {

			// If there's a condition specified and it returns false,
			// ignore this event
			if( typeof config.keyboardCondition === 'function' && config.keyboardCondition() === false ) {
			return true;
			}

			// Remember if auto-sliding was paused so we can toggle it
			var autoSlideWasPaused = autoSlidePaused;

			onUserInput( event );

			// Check if there's a focused element that could be using
			// the keyboard
			var activeElementIsCE = document.activeElement && document.activeElement.contentEditable !== 'inherit';
			var activeElementIsInput = document.activeElement && document.activeElement.tagName && /input\|textarea/i.test( document.activeElement.tagName );
			var activeElementIsNotes = document.activeElement && document.activeElement.className && /speaker-notes/i.test( document.activeElement.className);

			// Disregard the event if there's a focused element or a
			// keyboard modifier key is present
			if( activeElementIsCE \|\| activeElementIsInput \|\| activeElementIsNotes \|\| (event.shiftKey && event.keyCode !== 32) \|\| event.altKey \|\| event.ctrlKey \|\| event.metaKey ) return;

			// While paused only allow resume keyboard events; 'b', 'v', '.'
			var resumeKeyCodes = [66,86,190,191];
			var key;

			// Custom key bindings for togglePause should be able to resume
			if( typeof config.keyboard === 'object' ) {
			for( key in config.keyboard ) {
			if( config.keyboard[key] === 'togglePause' ) {
			resumeKeyCodes.push( parseInt( key, 10 ) );
			}
			}
			}

			if( isPaused() && resumeKeyCodes.indexOf( event.keyCode ) === -1 ) {
			return false;
			}

			var triggered = false;

			// 1. User defined key bindings
			if( typeof config.keyboard === 'object' ) {

			for( key in config.keyboard ) {

			// Check if this binding matches the pressed key
			if( parseInt( key, 10 ) === event.keyCode ) {

			var value = config.keyboard[ key ];

			// Callback function
			if( typeof value === 'function' ) {
			value.apply( null, [ event ] );
			}
			// String shortcuts to reveal.js API
			else if( typeof value === 'string' && typeof Reveal[ value ] === 'function' ) {
			Reveal[ value ].call();
			}

			triggered = true;

			}

			}

			}

			// 2. System defined key bindings
			if( triggered === false ) {

			// Assume true and try to prove false
			triggered = true;

			switch( event.keyCode ) {
			// p, page up
			case 80: case 33: navigatePrev(); break;
			// n, page down
			case 78: case 34: navigateNext(); break;
			// h, left
			case 72: case 37: navigateLeft(); break;
			// l, right
			case 76: case 39: navigateRight(); break;
			// k, up
			case 75: case 38: navigateUp(); break;
			// j, down
			case 74: case 40: navigateDown(); break;
			// home
			case 36: slide( 0 ); break;
			// end
			case 35: slide( Number.MAX_VALUE ); break;
			// space
			case 32: isOverview() ? deactivateOverview() : event.shiftKey ? navigatePrev() : navigateNext(); break;
			// return
			case 13: isOverview() ? deactivateOverview() : triggered = false; break;
			// two-spot, semicolon, b, v, period, Logitech presenter tools "black screen" button
			case 58: case 59: case 66: case 86: case 190: case 191: togglePause(); break;
			// f
			case 70: enterFullscreen(); break;
			// a
			case 65: if ( config.autoSlideStoppable ) toggleAutoSlide( autoSlideWasPaused ); break;
			default:
			triggered = false;
			}

			}

			// If the input resulted in a triggered action we should prevent
			// the browsers default behavior
			if( triggered ) {
			event.preventDefault && event.preventDefault();
			}
			// ESC or O key
			else if ( ( event.keyCode === 27 \|\| event.keyCode === 79 ) && features.transforms3d ) {
			if( dom.overlay ) {
			closeOverlay();
			}
			else {
			toggleOverview();
			}

			event.preventDefault && event.preventDefault();
			}

			// If auto-sliding is enabled we need to cue up
			// another timeout
			cueAutoSlide();

			}

			/**
			* Handler for the 'touchstart' event, enables support for
			* swipe and pinch gestures.
			*
			* @param {object} event
			*/
			function onTouchStart( event ) {

			if( isSwipePrevented( event.target ) ) return true;

			touch.startX = event.touches[0].clientX;
			touch.startY = event.touches[0].clientY;
			touch.startCount = event.touches.length;

			// If there's two touches we need to memorize the distance
			// between those two points to detect pinching
			if( event.touches.length === 2 && config.overview ) {
			touch.startSpan = distanceBetween( {
			x: event.touches[1].clientX,
			y: event.touches[1].clientY
			}, {
			x: touch.startX,
			y: touch.startY
			} );
			}

			}

			/**
			* Handler for the 'touchmove' event.
			*
			* @param {object} event
			*/
			function onTouchMove( event ) {

			if( isSwipePrevented( event.target ) ) return true;

			// Each touch should only trigger one action
			if( !touch.captured ) {
			onUserInput( event );

			var currentX = event.touches[0].clientX;
			var currentY = event.touches[0].clientY;

			// If the touch started with two points and still has
			// two active touches; test for the pinch gesture
			if( event.touches.length === 2 && touch.startCount === 2 && config.overview ) {

			// The current distance in pixels between the two touch points
			var currentSpan = distanceBetween( {
			x: event.touches[1].clientX,
			y: event.touches[1].clientY
			}, {
			x: touch.startX,
			y: touch.startY
			} );

			// If the span is larger than the desire amount we've got
			// ourselves a pinch
			if( Math.abs( touch.startSpan - currentSpan ) > touch.threshold ) {
			touch.captured = true;

			if( currentSpan < touch.startSpan ) {
			activateOverview();
			}
			else {
			deactivateOverview();
			}
			}

			event.preventDefault();

			}
			// There was only one touch point, look for a swipe
			else if( event.touches.length === 1 && touch.startCount !== 2 ) {

			var deltaX = currentX - touch.startX,
			deltaY = currentY - touch.startY;

			if( deltaX > touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
			touch.captured = true;
			navigateLeft();
			}
			else if( deltaX < -touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
			touch.captured = true;
			navigateRight();
			}
			else if( deltaY > touch.threshold ) {
			touch.captured = true;
			navigateUp();
			}
			else if( deltaY < -touch.threshold ) {
			touch.captured = true;
			navigateDown();
			}

			// If we're embedded, only block touch events if they have
			// triggered an action
			if( config.embedded ) {
			if( touch.captured \|\| isVerticalSlide( currentSlide ) ) {
			event.preventDefault();
			}
			}
			// Not embedded? Block them all to avoid needless tossing
			// around of the viewport in iOS
			else {
			event.preventDefault();
			}

			}
			}
			// There's a bug with swiping on some Android devices unless
			// the default action is always prevented
			else if( UA.match( /android/gi ) ) {
			event.preventDefault();
			}

			}

			/**
			* Handler for the 'touchend' event.
			*
			* @param {object} event
			*/
			function onTouchEnd( event ) {

			touch.captured = false;

			}

			/**
			* Convert pointer down to touch start.
			*
			* @param {object} event
			*/
			function onPointerDown( event ) {

			if( event.pointerType === event.MSPOINTER_TYPE_TOUCH \|\| event.pointerType === "touch" ) {
			event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
			onTouchStart( event );
			}

			}

			/**
			* Convert pointer move to touch move.
			*
			* @param {object} event
			*/
			function onPointerMove( event ) {

			if( event.pointerType === event.MSPOINTER_TYPE_TOUCH \|\| event.pointerType === "touch" ) {
			event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
			onTouchMove( event );
			}

			}

			/**
			* Convert pointer up to touch end.
			*
			* @param {object} event
			*/
			function onPointerUp( event ) {

			if( event.pointerType === event.MSPOINTER_TYPE_TOUCH \|\| event.pointerType === "touch" ) {
			event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
			onTouchEnd( event );
			}

			}

			/**
			* Handles mouse wheel scrolling, throttled to avoid skipping
			* multiple slides.
			*
			* @param {object} event
			*/
			function onDocumentMouseScroll( event ) {

			if( Date.now() - lastMouseWheelStep > 600 ) {

			lastMouseWheelStep = Date.now();

			var delta = event.detail \|\| -event.wheelDelta;
			if( delta > 0 ) {
			navigateNext();
			}
			else if( delta < 0 ) {
			navigatePrev();
			}

			}

			}

			/**
			* Clicking on the progress bar results in a navigation to the
			* closest approximate horizontal slide using this equation:
			*
			* ( clickX / presentationWidth ) * numberOfSlides
			*
			* @param {object} event
			*/
			function onProgressClicked( event ) {

			onUserInput( event );

			event.preventDefault();

			var slidesTotal = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).length;
			var slideIndex = Math.floor( ( event.clientX / dom.wrapper.offsetWidth ) * slidesTotal );

			if( config.rtl ) {
			slideIndex = slidesTotal - slideIndex;
			}

			slide( slideIndex );

			}

			/**
			* Event handler for navigation control buttons.
			*/
			function onNavigateLeftClicked( event ) { event.preventDefault(); onUserInput(); navigateLeft(); }
			function onNavigateRightClicked( event ) { event.preventDefault(); onUserInput(); navigateRight(); }
			function onNavigateUpClicked( event ) { event.preventDefault(); onUserInput(); navigateUp(); }
			function onNavigateDownClicked( event ) { event.preventDefault(); onUserInput(); navigateDown(); }
			function onNavigatePrevClicked( event ) { event.preventDefault(); onUserInput(); navigatePrev(); }
			function onNavigateNextClicked( event ) { event.preventDefault(); onUserInput(); navigateNext(); }

			/**
			* Handler for the window level 'hashchange' event.
			*
			* @param {object} [event]
			*/
			function onWindowHashChange( event ) {

			readURL();

			}

			/**
			* Handler for the window level 'resize' event.
			*
			* @param {object} [event]
			*/
			function onWindowResize( event ) {

			layout();

			}

			/**
			* Handle for the window level 'visibilitychange' event.
			*
			* @param {object} [event]
			*/
			function onPageVisibilityChange( event ) {

			var isHidden = document.webkitHidden \|\|
			document.msHidden \|\|
			document.hidden;

			// If, after clicking a link or similar and we're coming back,
			// focus the document.body to ensure we can use keyboard shortcuts
			if( isHidden === false && document.activeElement !== document.body ) {
			// Not all elements support .blur() - SVGs among them.
			if( typeof document.activeElement.blur === 'function' ) {
			document.activeElement.blur();
			}
			document.body.focus();
			}

			}

			/**
			* Invoked when a slide is and we're in the overview.
			*
			* @param {object} event
			*/
			function onOverviewSlideClicked( event ) {

			// TODO There's a bug here where the event listeners are not
			// removed after deactivating the overview.
			if( eventsAreBound && isOverview() ) {
			event.preventDefault();

			var element = event.target;

			while( element && !element.nodeName.match( /section/gi ) ) {
			element = element.parentNode;
			}

			if( element && !element.classList.contains( 'disabled' ) ) {

			deactivateOverview();

			if( element.nodeName.match( /section/gi ) ) {
			var h = parseInt( element.getAttribute( 'data-index-h' ), 10 ),
			v = parseInt( element.getAttribute( 'data-index-v' ), 10 );

			slide( h, v );
			}

			}
			}

			}

			/**
			* Handles clicks on links that are set to preview in the
			* iframe overlay.
			*
			* @param {object} event
			*/
			function onPreviewLinkClicked( event ) {

			if( event.currentTarget && event.currentTarget.hasAttribute( 'href' ) ) {
			var url = event.currentTarget.getAttribute( 'href' );
			if( url ) {
			showPreview( url );
			event.preventDefault();
			}
			}

			}

			/**
			* Handles click on the auto-sliding controls element.
			*
			* @param {object} [event]
			*/
			function onAutoSlidePlayerClick( event ) {

			// Replay
			if( Reveal.isLastSlide() && config.loop === false ) {
			slide( 0, 0 );
			resumeAutoSlide();
			}
			// Resume
			else if( autoSlidePaused ) {
			resumeAutoSlide();
			}
			// Pause
			else {
			pauseAutoSlide();
			}

			}


			// --------------------------------------------------------------------//
			// ------------------------ PLAYBACK COMPONENT ------------------------//
			// --------------------------------------------------------------------//


			/**
			* Constructor for the playback component, which displays
			* play/pause/progress controls.
			*
			* @param {HTMLElement} container The component will append
			* itself to this
			* @param {function} progressCheck A method which will be
			* called frequently to get the current progress on a range
			* of 0-1
			*/
			function Playback( container, progressCheck ) {

			// Cosmetics
			this.diameter = 100;
			this.diameter2 = this.diameter/2;
			this.thickness = 6;

			// Flags if we are currently playing
			this.playing = false;

			// Current progress on a 0-1 range
			this.progress = 0;

			// Used to loop the animation smoothly
			this.progressOffset = 1;

			this.container = container;
			this.progressCheck = progressCheck;

			this.canvas = document.createElement( 'canvas' );
			this.canvas.className = 'playback';
			this.canvas.width = this.diameter;
			this.canvas.height = this.diameter;
			this.canvas.style.width = this.diameter2 + 'px';
			this.canvas.style.height = this.diameter2 + 'px';
			this.context = this.canvas.getContext( '2d' );

			this.container.appendChild( this.canvas );

			this.render();

			}

			/**
			* @param value
			*/
			Playback.prototype.setPlaying = function( value ) {

			var wasPlaying = this.playing;

			this.playing = value;

			// Start repainting if we weren't already
			if( !wasPlaying && this.playing ) {
			this.animate();
			}
			else {
			this.render();
			}

			};

			Playback.prototype.animate = function() {

			var progressBefore = this.progress;

			this.progress = this.progressCheck();

			// When we loop, offset the progress so that it eases
			// smoothly rather than immediately resetting
			if( progressBefore > 0.8 && this.progress < 0.2 ) {
			this.progressOffset = this.progress;
			}

			this.render();

			if( this.playing ) {
			features.requestAnimationFrameMethod.call( window, this.animate.bind( this ) );
			}

			};

			/**
			* Renders the current progress and playback state.
			*/
			Playback.prototype.render = function() {

			var progress = this.playing ? this.progress : 0,
			radius = ( this.diameter2 ) - this.thickness,
			x = this.diameter2,
			y = this.diameter2,
			iconSize = 28;

			// Ease towards 1
			this.progressOffset += ( 1 - this.progressOffset ) * 0.1;

			var endAngle = ( - Math.PI / 2 ) + ( progress * ( Math.PI * 2 ) );
			var startAngle = ( - Math.PI / 2 ) + ( this.progressOffset * ( Math.PI * 2 ) );

			this.context.save();
			this.context.clearRect( 0, 0, this.diameter, this.diameter );

			// Solid background color
			this.context.beginPath();
			this.context.arc( x, y, radius + 4, 0, Math.PI * 2, false );
			this.context.fillStyle = 'rgba( 0, 0, 0, 0.4 )';
			this.context.fill();

			// Draw progress track
			this.context.beginPath();
			this.context.arc( x, y, radius, 0, Math.PI * 2, false );
			this.context.lineWidth = this.thickness;
			this.context.strokeStyle = '#666';
			this.context.stroke();

			if( this.playing ) {
			// Draw progress on top of track
			this.context.beginPath();
			this.context.arc( x, y, radius, startAngle, endAngle, false );
			this.context.lineWidth = this.thickness;
			this.context.strokeStyle = '#fff';
			this.context.stroke();
			}

			this.context.translate( x - ( iconSize / 2 ), y - ( iconSize / 2 ) );

			// Draw play/pause icons
			if( this.playing ) {
			this.context.fillStyle = '#fff';
			this.context.fillRect( 0, 0, iconSize / 2 - 4, iconSize );
			this.context.fillRect( iconSize / 2 + 4, 0, iconSize / 2 - 4, iconSize );
			}
			else {
			this.context.beginPath();
			this.context.translate( 4, 0 );
			this.context.moveTo( 0, 0 );
			this.context.lineTo( iconSize - 4, iconSize / 2 );
			this.context.lineTo( 0, iconSize );
			this.context.fillStyle = '#fff';
			this.context.fill();
			}

			this.context.restore();

			};

			Playback.prototype.on = function( type, listener ) {
			this.canvas.addEventListener( type, listener, false );
			};

			Playback.prototype.off = function( type, listener ) {
			this.canvas.removeEventListener( type, listener, false );
			};

			Playback.prototype.destroy = function() {

			this.playing = false;

			if( this.canvas.parentNode ) {
			this.container.removeChild( this.canvas );
			}

			};


			// --------------------------------------------------------------------//
			// ------------------------------- API --------------------------------//
			// --------------------------------------------------------------------//


			Reveal = {
			VERSION: VERSION,

			initialize: initialize,
			configure: configure,
			sync: sync,

			// Navigation methods
			slide: slide,
			left: navigateLeft,
			right: navigateRight,
			up: navigateUp,
			down: navigateDown,
			prev: navigatePrev,
			next: navigateNext,

			// Fragment methods
			navigateFragment: navigateFragment,
			prevFragment: previousFragment,
			nextFragment: nextFragment,

			// Deprecated aliases
			navigateTo: slide,
			navigateLeft: navigateLeft,
			navigateRight: navigateRight,
			navigateUp: navigateUp,
			navigateDown: navigateDown,
			navigatePrev: navigatePrev,
			navigateNext: navigateNext,

			// Forces an update in slide layout
			layout: layout,

			// Randomizes the order of slides
			shuffle: shuffle,

			// Returns an object with the available routes as booleans (left/right/top/bottom)
			availableRoutes: availableRoutes,

			// Returns an object with the available fragments as booleans (prev/next)
			availableFragments: availableFragments,

			// Toggles a help overlay with keyboard shortcuts
			toggleHelp: toggleHelp,

			// Toggles the overview mode on/off
			toggleOverview: toggleOverview,

			// Toggles the "black screen" mode on/off
			togglePause: togglePause,

			// Toggles the auto slide mode on/off
			toggleAutoSlide: toggleAutoSlide,

			// State checks
			isOverview: isOverview,
			isPaused: isPaused,
			isAutoSliding: isAutoSliding,

			// Adds or removes all internal event listeners (such as keyboard)
			addEventListeners: addEventListeners,
			removeEventListeners: removeEventListeners,

			// Facility for persisting and restoring the presentation state
			getState: getState,
			setState: setState,

			// Presentation progress
			getSlidePastCount: getSlidePastCount,

			// Presentation progress on range of 0-1
			getProgress: getProgress,

			// Returns the indices of the current, or specified, slide
			getIndices: getIndices,

			// Returns an Array of all slides
			getSlides: getSlides,

			// Returns the total number of slides
			getTotalSlides: getTotalSlides,

			// Returns the slide element at the specified index
			getSlide: getSlide,

			// Returns the slide background element at the specified index
			getSlideBackground: getSlideBackground,

			// Returns the speaker notes string for a slide, or null
			getSlideNotes: getSlideNotes,

			// Returns the previous slide element, may be null
			getPreviousSlide: function() {
			return previousSlide;
			},

			// Returns the current slide element
			getCurrentSlide: function() {
			return currentSlide;
			},

			// Returns the current scale of the presentation content
			getScale: function() {
			return scale;
			},

			// Returns the current configuration object
			getConfig: function() {
			return config;
			},

			// Helper method, retrieves query string as a key/value hash
			getQueryHash: function() {
			var query = {};

			location.search.replace( /[A-Z0-9]+?=([\w\.%-]*)/gi, function(a) {
			query[ a.split( '=' ).shift() ] = a.split( '=' ).pop();
			} );

			// Basic deserialization
			for( var i in query ) {
			var value = query[ i ];

			query[ i ] = deserialize( unescape( value ) );
			}

			return query;
			},

			// Returns true if we're currently on the first slide
			isFirstSlide: function() {
			return ( indexh === 0 && indexv === 0 );
			},

			// Returns true if we're currently on the last slide
			isLastSlide: function() {
			if( currentSlide ) {
			// Does this slide has next a sibling?
			if( currentSlide.nextElementSibling ) return false;

			// If it's vertical, does its parent have a next sibling?
			if( isVerticalSlide( currentSlide ) && currentSlide.parentNode.nextElementSibling ) return false;

			return true;
			}

			return false;
			},

			// Checks if reveal.js has been loaded and is ready for use
			isReady: function() {
			return loaded;
			},

			// Forward event binding to the reveal DOM element
			addEventListener: function( type, listener, useCapture ) {
			if( 'addEventListener' in window ) {
			( dom.wrapper \|\| document.querySelector( '.reveal' ) ).addEventListener( type, listener, useCapture );
			}
			},
			removeEventListener: function( type, listener, useCapture ) {
			if( 'addEventListener' in window ) {
			( dom.wrapper \|\| document.querySelector( '.reveal' ) ).removeEventListener( type, listener, useCapture );
			}
			},

			// Programatically triggers a keyboard event
			triggerKey: function( keyCode ) {
			onDocumentKeyDown( { keyCode: keyCode } );
			},

			// Registers a new shortcut to include in the help overlay
			registerKeyboardShortcut: function( key, value ) {
			keyboardShortcuts[key] = value;
			}
			};

			return Reveal;

			}));

R3683/js/reveal.js53ceff8dd557line-numbering-platex

reveal.jsView Options

R3683/js/reveal.js
53ceff8dd557line-numbering-platex

reveal.js
View Options