We need a way of testing media query rules in JavaScript, and a way of generating events when a new rule matches. There’s a specification for exactly this: there’s matchMedia to see if a query matches, and MediaQueryList with MediaQueryListeners to detect and respond to changes.

matchMedia has support in Chrome, Firefox 6+ and Safari 5.1+ and there’s even a polyfill (by Scott Jehl, Paul Irish, Nicholas Zakas) for other browsers. So we can happily perform our one off tests in JavaScript (probably on page load):

if (matchMedia('only screen and (max-width: 480px)').matches) {
  // iphone specific JS
}

However media query list listeners (that’s a mouthful) are only supported in Firefox 6+. This is the magic of firing events when something changes, it completes the circle.

All is not lost, there is another way of using CSS to generate events and that’s through CSS transitions. When a CSS transition ends it fires a transitionEnd event (webkitTransitionEnd, oTransitionEnd, transitionend) on the appropriate element. Now consider a transition that occurs only when a media query is applied. Hey presto, we have a JavaScript event triggered by media query rules, however complicated or convoluted that rule may be. This rocks and can form the basis of a MediaQueryList polyfill.

Simple transition CSS and event listener

.mq {
-webkit-transition: width 0.001ms;
-moz-transition: width 0.001ms;
-o-transition: width 0.001ms;
transition: width 0.001ms;
width: 0;
}

@media all and (max-width: 480px) {
.mq {
width: 1px;
}
}

var mq = document.querySelectorAll('.mq')[0],
mq.addEventListener('webkitTransitionEnd', function() {
	/* Transition ends, media query matched */
}, false);

Proof of concept

I’ve taken the excellent matchMedia polyfill and quickly hacked together a version that includes transition events and a callback.

Proof of concept demo
(and on Github)

mql('all and (max-width: 700px)', callback);

Pass in a media query string and callback. It immediately returns the test result and the callback will fire whenever the test result changes, the only argument being the MediaQueryList object. This isn’t a polyfill because it doesn’t yet match the specification, if it did the originally returned MQL object would have addListener and removeListener functions (that’s a work in progress).

The CSS transitions are instantaneous via a duration of a little larger than 0, I’ve chosen 0.001ms.

Element transitions are bidirectional, so the event fires when the rule matches and when it no longer matches. Every time the event fires a test is performed to determine state, this is easy using matchMedia.

The CSS transition event tells us which element triggered the transition but no details about the media query rules that governed it. So we use unique elements for each rule to connect the dots.

.mq {
-webkit-transition: width 0.001ms;
-moz-transition: width 0.001ms;
-o-transition: width 0.001ms;
transition: width 0.001ms;
width: 0;
}

mql = (function(doc, undefined){

  var bool,
      docElem  = doc.documentElement,
      refNode  = docElem.firstElementChild || docElem.firstChild,
      idCounter = 0;

  return function(q, cb){

	var id = 'mql-' + idCounter++,
	    callback = function() {
		cb({ matches: (div.offsetWidth == 42), media: q });
	    },
	    div = doc.createElement('div');

	div.className = 'mq';
	div.style.cssText = "position:absolute;top:-100em";
	div.id = id;
        div.innerHTML = '&shy;<style media="'+q+'"> #'+id+' { width: 42px; }</style>';

	div.addEventListener('webkitTransitionEnd', callback, false);
	div.addEventListener('transitionend', callback, false); //Firefox
	div.addEventListener('oTransitionEnd', callback, false); //Opera

        docElem.insertBefore(div, refNode);
        //don't delete the div, we need to listen to events
        return { matches: div.offsetWidth == 42, media: q };
  };

})(document);

Demo code

$(function() {

    var $dynamic = $('.dynamic');
    mql('all and (max-width: 700px)', change);
    mql('all and (max-width: 500px)', change);
    mql('all and (min-width: 1200px)', change);

    function change(mql) {
        console.log(mql);
        $dynamic.prepend('<p>' + mql.media + ' &mdash; ' + mql.matches + '</p>');
    }
});

Support

Obviously for this to work we need both CSS transitions and media query support in the browser. Looking at caniuse.com and QuirksMode this technique should be supported by: Chrome, Android (2.1+), Opera (10.6+), Opera Mobile (10.0+), Firefox (4+), Safari (3.2+) and iOS (3.2+). Samsung’s Dolfin and Blackberry 6 support CSS animations, I presume that means transitions too, but I can’t easily test.

Of course, IE is lagging behind, as always. IE9 supports media queries but it has no transition support, that’s coming in IE10.

CSS Modal Experiment

In this experiment, clicking an ‘open’ link pops up a dialogue with a smooth hardware accelerated bounce (where supported). When open all other elements on the page are non-clickable. Closing the modal is also animated, with a minimise effect. I’ve marked up the modal using <aside>, but depending on the purpose of yours, <nav> or probably <details> might be more appropriate.

Of course, using images and JS will only make the modal better, and something like hitting ESC to close will never be reproduced in CSS. Pure CSS is rarely the best production-ready solution.

How to

The :target pseudo-selector changes the style of a targeted element. Combining a link pointing to an element with :target and altering visibility/display/opacity gives a hide/show mechanism. To facilitate the animations, which were jerky when using display:none, I’ve used a combination of :target, opacity and pointer events:

.modal {
opacity: 0;
pointer-events: none;
}

.modal:target {
opacity: 1;
pointer-events: auto;
}

The modal is two parts, one part container, one part content. Ideally the container would be generated using a pseudo-element, but I haven’t got that working yet. The container spreads across the whole page and dims the background with rgba. A high z-index puts the modal on top.

.modal {
position: fixed;
top: 0;
left: 0;
right: 0;
bottom: 0;
background: rgba(0,0,0,0.5);
z-index: 10000;
…
}

The content is positioned roughly in the middle and is prettified with a sprinkling of text shadow, border radius, box shadow and gradient.

There are two animations, one named “bounce” (scale to slightly larger than normal, then fall back) and another, “minimise”, which act on the content part. These combine with a separate opacity transition on the container.

The simple opacity transition:

.modal {
…
-webkit-transition: opacity 500ms ease-in;
-moz-transition: opacity 500ms ease-in;
transition: opacity 500ms ease-in;
}

The scaling animations, although only 2D, uses scale3d for hardware acceleration. To make the bounce more realistic box shadow is also animated, which comes with a performance hit.

@-webkit-keyframes bounce {
  0% {
  	-webkit-transform: scale3d(0.1,0.1,1);
  	-webkit-box-shadow: 0 3px 20px rgba(0,0,0,0.9);
  }
  55% {
  	-webkit-transform: scale3d(1.08,1.08,1);
  	-webkit-box-shadow: 0 10px 20px rgba(0,0,0,0);
  }
  75% {
  	-webkit-transform: scale3d(0.95,0.95,1);
  	-webkit-box-shadow: 0 0 20px rgba(0,0,0,0.9);
  }
  100% {
  	-webkit-transform: scale3d(1,1,1);
  	-webkit-box-shadow: 0 3px 20px rgba(0,0,0,0.9);
  }
}

@-webkit-keyframes minimise {
  0% {
  	-webkit-transform: scale3d(1,1,1);
  }
  100% {
  	-webkit-transform: scale3d(0.1,0.1,1);
  }
}

To change the animation on open we can use the cascade and override the default animation with a more specific one, using :target again:

.modal > div {
…
-webkit-animation: minimise 500ms linear;
}

.modal:target > div {
-webkit-animation-name: bounce;
}

The close button is a hidden close link with a styled ::after pseudo-element that scales on hover/focus/active. As we’re hiding the original close link, there are some hoops to jump through to make the :focus state change on the pseudo-element. The traditional clip, text indent or visibility hidden methods all fail, and I’ve resorted to color:transparent and some specific focus styles to override the confused native ones.

.modal a[href="#close"] {
…
color: transparent;
}

.modal a[href="#close"]:after {
content: 'X';
display: block;
…
}

.modal a[href="#close"]:focus:after,
.modal a[href="#close"]:hover:after {
-webkit-transform: scale(1.1,1.1);
-moz-transform: scale(1.1,1.1);
}

.modal a[href="#close"]:focus:after {
outline: 1px solid #000;
}

Caveats

It won’t work in IE8 and below, there’s no pointer-event support and opacity is poorly implemented. IE9 supports :target but no pointer-events. Some IE specific styles could easily switch the opacity toggle to a display or visibility one.

Users will still be able to tab through the links in the background and activate them. This only becomes an issue if you ignore the focus state…

As I alluded to at the start, some JS hooks for keyboard interaction wouldn’t go amiss, ESC to close and something to pull focus to the current modal and then back again on close.

The close button would probably look better with an image and the markup uses an extra containing element, which is always undesirable.

Animations can be great, in small quantities, but something that animates too much and gets in the way of functionality is a major drawback for users. It would be quite easy to go overboard with this.

Update — I’ve added a follow up post that addresses some of the caveats and makes this a little more cross browser compatible: CSS Modal Follow Up

3D CSS Sphere
Works in the latest Safari and iOS (just about runs on an iPhone 4).

Recently I’ve been looking at creating applicable 3D carousels. These rely on positioning panels in a circle around a central point (ie. rotation about the Y-axis), I put these panels in an unordered list. A natural extension is to duplicate each <ul> and rotate about the X-axis. With ‘A’ rounds (or lists), and ‘B’ panels per round (<li>s), I built a script that would distribute these in a circular manner, panels about Y-axis, lists about the X-axis, creating a sphere.

The more elements per round and the more rounds, the smoother the sphere. But this soon stacks up and kills Safari. The optimum numbers have been about 9 rounds and 30 panels per round for a decent looking sphere, but that’s 279 3D elements and Safari starts to choke. Allowing the panels to overlap eases this somewhat and leads to a tighter sphere but it still appears blocky.

The biggest gains come with border radius. Using a huge radius that made each panel circular the sphere suddenly gained a lovely curvature, and the number of rounds and panels could be reduced. In the experiment I use 8 rounds and 24 panels (200 elements). This doesn’t start choking until I start aggressively animating.

Playing with this I’ve built a few different styles of sphere. In the experiment I’ve included the blocky “square” version, along with the smoothed out border radius one (default). Marking panels white, and a few black can create a nice eye-ball effect.

Also included in the experiment are versions showing a single round and another style named “contact”. This takes two lists and animates them like the space transportation device in the Jodie Foster movie of the same name.

Animating the border radius on all 192 panels (if your machine can cope), gives a neat kaleidoscope effect, also included in the experiment.

Code

The generated HTML is simply a couple of <div>s containing lists:

<div id="sphere">
	<div class="container">
		<ul>
			<li></li>
			<li></li>
			…
		</ul>
		…
	</div>
</div>

To transform each set of panels into a circle the total number is divided by 360 to get the angle of rotation. Merely rotating will put all panels on top of each other, translating in the Z axis will move them out from the centre point. The correct translation distance so the panels slightly overlap (i.e. the circle radius) is worked out with some simple trigonometry. Lists are rotated in the X axis, simply the number of lists divided by 360.

Looping through each panel for each list, the angles of rotation are gradually increased by the calculated increments and applied to the elements:

var panels = p || this.panels,
rounds = r || this.rounds,
rotationPerPanel = 360/panels,
rotationPerRound = 360/2/rounds,
yRotation, xRotation,
width = this.panelWidth,
zTranslate = (width/2) / Math.tan(rotationPerPanel * Math.PI/180),
$container = this.el,
$ul, $li, i, j;

this.el.html('');
for(i = 0; i < rounds; i++) {
	$ul = $('<ul>');
	xRotation = rotationPerRound * i;
	$ul[0].style.webkitTransform = "rotateX("+ xRotation + "deg)";
	for(j = 0; j < panels; j++) {
		$li = $('<li>');
		yRotation = rotationPerPanel * j;
		$li[0].style.webkitTransform = "rotateY("+ yRotation +"deg)
                         translateZ("+ zTranslate +"px)";
		$ul.append($li);
	}
	$container.append($ul);
}

To achieve the 3D effect we give #sphere some perspective, which forms the containing block. A second container transitions between different transforms, letting us rotate the sphere. The complicated transform parts are applied inline via the JavaScript above, but each list element needs preserve-3d so its direct descendants are transformed in the same 3D space (rather than in 2D).

#sphere {
width: 100px;
height: 100px;
margin: 200px auto;
-webkit-perspective: 800;
}

.container {
width: 100px;
height: 100px;
-webkit-transition: -webkit-transform 200ms linear;
-webkit-transform-style: preserve-3d;
}

.container > ul {
-webkit-transform-style: preserve-3d;
width: 100%;
height: 100%;
position: absolute;
}

.container li {
width: 98px;
height: 98px;
position: absolute;
display: block;
background: #000;
border: 1px solid #fff;
opacity: 0.1;
border-radius: 50px;
}

An update on the original 3D cube (from July 2009 no less), I’ve added touch gesture support (iOS) and click-and-drag behaviour. Animation is incredibly smooth on the iPhone, even the 3G model. Arrow key presses will still rotate the cube, and ESC will reset it.

One year on and the cube still only works in Safari. Chrome, which says it supports webkit-perspective and webkit-transform, still renders differently. Firefox doesn’t support 3D transforms yet.

It works relatively simply: on click the start co-ordinates are saved and on drag the difference between current drag position and starting co-ordinates are applied to the cube as a transform, which is completed after the specified transition duration. Many thanks to Remy Sharp and his rubik’s experiment, which got me started with a lot of the basics.

Touch tweaks

Pixel values for touch positions are found in event.originalEvent.touches[0].pageX, instead of event.pageX. Using ‘start minus current’ pixel values led the cube to rotate more than intended on the iPhone. To correct, and for intuitive behaviour, the difference is reduced by a factor of four.

JavaScript prevents single touch default events — e.g. scrolling and text selection, but if it detects more than one touch (event.originalEvent.touches.length) the cube won’t rotate, so pinch and zoom will still work. This is a compromise.

A 200ms transition duration suits the browser, but on touch devices it felt sluggish, so I’ve upped it to 50ms so the cube is always at your finger-tips.

Better CSS

The cube is created exactly as before, but I’ve simplified the markup a little — dropping the face and number class names in favour of CSS3 selectors:

#cube > div:first-child  {
-webkit-transform: rotateX(90deg) translateZ(200px);
}

#cube > div:nth-child(2) {
-webkit-transform: translateZ(200px);
}

#cube > div:nth-child(3) {
-webkit-transform: rotateY(90deg) translateZ(200px);
text-align: center;
}

#cube > div:nth-child(4) {
-webkit-transform: rotateY(180deg) translateZ(200px);
}

#cube > div:nth-child(5) {
-webkit-transform: rotateY(-90deg) translateZ(200px);
}

#cube > div:nth-child(6) {
-webkit-transform: rotateX(-90deg) rotate(180deg) translateZ(200px) ;
}

Any questions?

This is quite a speedy write-up, if anything needs explaining I’m happy to go into a bit more detail.

Last week WebKit included the much anticipated (at least on my part) 3D transforms in its latest nightly build, announced practically alongside the awesome Snow Stack demo that provides a 3D interface for browsing Flickr images (use left, right and space-bar). Today the Surfin Safari blog has updated with some more exciting demos, including “Morphin Power Cubes” and “Poster Circle”. It is now possible to create all sorts of crazy three-dimensional and animated user interfaces; the power comes largely in -webkit-perspective and a number of updated transforms–adapted to incorporate the Z axis.

Since working on the 3D cube using 2D transforms back in April I’ve experimented with perspective to create something more powerful, playing around with 3D transforms on the iPhone a few times (e.g. this early rotating demo). Now I’ve got something worth sharing.

A 3D cube can be created solely in CSS, with all six faces. Using JavaScript to detect key presses and update inline styles this cube can be intuitively navigated.

Result

A 3D cube that rotates using the Up, Down, Left and Right arrow keys.
Supported browsers: WebKit Nightly r46042+

How To

I’ll start with the markup, because it’s simple. Each of the six cube faces is given a face class and another relating to it’s number. These six faces sit within a cube container, which sits in another wrapper, each is necessary.

<div id="experiment">
	<div id="cube">
		<div class="face one">
			One face
		</div>
		<div class="face two">
			Up, down, left, right
		</div>
		<div class="face three">
			Lorem ipsum.
		</div>
		<div class="face four">
			New forms of navigation are fun.
		</div>
		<div class="face five">
			Rotating 3D cube
		</div>
		<div class="face six">
			More content
		</div>
	</div>
</div>

The outer wrapper serves as a camera, on which you apply some perspective — appropriate 3D transformations are then applied to descendants. -webkit-perspective defines the depth of the Z-plane and relative sizes of elements above and below it, -webkit-perspective-origin specifies the perspective’s origin. View a perspective example (webkit.org)

    #experiment {
      -webkit-perspective: 800;
      -webkit-perspective-origin: 50% 200px;
    }

The second container, the actual cube, has a specified height, margin, position, etc. as usual. The height and width are necessary to create some confines for the cube face transformations — alternatively the width defaults to 100% and the cube’s appearance would vary with window width. -webkit-transition (documentation) defines the animated property, duration and timing-function — we’re animating the 3d transformation (via -webkit-transform) linearly for two seconds. -webkit-transform-style determines whether child elements lie flat against their parent (“flat”) or remain in 3D space (“preserve-3d”).

    #cube {
      position: relative;
      margin: 0 auto;
      height: 400px;
      width: 400px;
      -webkit-transition: -webkit-transform 2s linear;
      -webkit-transform-style: preserve-3d;
    }

Using the .face class common styles are applied to the six sides; coloring, size, padding, etc. Importantly they are each positioned absolutely, relative to the cube container. The background rgba property is included to make the cube look pretty and transparent.

    .face {
      position: absolute;
      height: 360px;
      width: 360px;
      padding: 20px;
      background-color: rgba(50, 50, 50, 0.7);
    }

Each of the faces, one through six, needs to be rotated in 3D space to its correct starting position. Using translateZ the elements are brought 200px (half their width) off the Z-plane. Each of the faces must be at 90 degrees. Rotating solely in the X plane positions the top and bottom faces (one, six), before rotating the last four faces in the Y plane, much like origami. The extra rotate on the sixth face rotates the content in 2D space to correct its orientation.

    #cube .one  {
      -webkit-transform: rotateX(90deg) translateZ(200px);
    }

    #cube .two {
      -webkit-transform: translateZ(200px);
    }

    #cube .three {
      -webkit-transform: rotateY(90deg) translateZ(200px);
    }

    #cube .four {
      -webkit-transform: rotateY(180deg) translateZ(200px);
    }

    #cube .five {
      -webkit-transform: rotateY(-90deg) translateZ(200px);
    }

    #cube .six {
      -webkit-transform: rotateX(-90deg) translateZ(200px) rotate(180deg);
    }

Our cube is now complete — but it doesn’t move! With a keydown event listener we can increment X and Y angles based on different key presses, before applying them as inline styles on the cube container. In combination with the transition effect on #cube, all six faces rotate in sync from their original position to the newly defined angle, creating a seamless 3D cube interface.

  	var xAngle = 0, yAngle = 0;
	document.addEventListener('keydown', function(e)
	{
		switch(e.keyCode)
		{

			case 37: // left
				yAngle -= 90;
				break;

			case 38: // up
				xAngle += 90;
				break;

			case 39: // right
				yAngle += 90;
				break;

			case 40: // down
				xAngle -= 90;
				break;
		};

		$('cube').style.webkitTransform = "rotateX("+xAngle+"deg) rotateY("+yAngle+"deg)";
	}, false);

Result

CSS3 Accordion
Works in browsers that support the :target pseudo-class, see the Quirks Mode compatibility tables. Animation works in recent WebKit based browsers.

How To

Each part of the accordion has an ID, heading and content region. The header includes a link that matches the section’s ID, whilst the content is wrapped in a container which will control its display.

<div class="accordion">
	<h2>Accordion Demo</h2>
	<div id="one" class="section">
		<h3>
			<a href="#one">Heading 1</a>
		</h3>
		<div>
			<p>Content</p>
		</div>
	</div>
	<div id="two" class="section">
		<h3>
			<a href="#two">Heading 2</a>
		</h3>
		<div>
			<p>Content</p>
		</div>
	</div>
</div>

The CSS then relies on the :target pseudo-class to apply different styles to the chosen section — increasing the height and, in large content cases, altering the overflow behaviour to allow scrolling. To animate the opening and closing of sections the -webkit-transition property is needed (documentation), in this case acting on the height attribute for a duration of 0.3 seconds using the ease-in timing function.

Stripping out the styling, the CSS boils down to:

.accordion h3 + div {
	height: 0;
	overflow: hidden;
	-webkit-transition: height 0.3s ease-in;
}

.accordion :target h3 + div {
	height: 100px;
}

.accordion .section.large:target h3 + div {
	overflow: auto;
}

Critique

Obviously this approach has its limitations. Multiple open accordions on one page wouldn’t be possible — restricted by a URI’s one fragment identifier limit; as one accordion opens the other would lose the target and automatically close. Similarly, pages that use a fragment identifier for everyday use will notice oddities — take for instance when using top links to return to the top of the page, any accordion would, in this case, reset. Other uses include accessibility links and simulated page histories when using Ajax.

The impression of a three dimensional cube can be created using modern CSS techniques, without the need for JavaScript, imagery, canvas or SVG. Using the proprietary transform property to skew and rotate shaded rectangles, individual cube faces can combine to form a 3D object. Currently only supported in recent WebKit and Gecko based browsers, most importantly Firefox 3.5+ -moz-transform (documentation) and Safari 3.2+ -webkit-transform (documentation).

To demonstrate the power of this effect a second experiment with multiple cubes and proprietary WebKit transitions is also available.

Results

A 3D cube created with CSS
Update (June 7th): Altered CSS slightly to use skew(x,y) rather than skewY, the latter of which is not supported in Safari 3 / Chrome.
Supported browsers: Safari 3.2+, Google Chrome, Firefox 3.5+

Experiment with multiple cubes and CSS transitions, still no JavaScript
Supported browsers: Safari 4+, Google Chrome

How To

Similar to my previous experiments, the HTML markup is very simple. Each of the faces has its own DIV, class and content. The top face requires some extra markup to aid the transformation, more on that shortly.

<div class="cube">
	<div class="topFace">
		<div>
			Content
		</div>
	</div>
	<div class="leftFace">
		Content
	</div>
	<div class="rightFace">
		Content
	</div>
</div>

A short disclaimer, the geometry in this example is ‘fudged’, in that the values have been adjusted to appear roughly correct. I know that the dimensions are slightly out of whack, this is merely to save my head from mathematics and to get the concept out there quickly for people to see. With that said, let’s crack on with the CSS.

Each of the three rectangles is given a slightly different shade of gray to give the impression of depth, in this example the left face is in shadow. The faces are each positioned absolutely, relative to the cube container. Each face is 200 x 200 pixels, including 10 pixels of padding.

.cube {
	position: relative;
	top: 200px;
}

.rightFace,
.leftFace,
.topFace div {
	padding: 10px;
	width: 180px;
	height: 180px;
}

.rightFace,
.leftFace,
.topFace {
	position: absolute;
}

Now for the fun bit. The left and right rectangles are skewed by ±30˚ along the vertical axis, with the right face shifted left by 200px, cleanly lining up the two edges to create a corner that is center aligned.

.leftFace {
	-webkit-transform: skewY(30deg);
	-moz-transform: skewY(30deg);
	background-color: #ccc;
}

.rightFace {
	-webkit-transform: skewY(-30deg);
	-moz-transform: skewY(-30deg);
	background-color: #ddd;
	left: 200px;
}

The top face proves more problematic; it needs to be skewed, scaled, rotated and positioned. The skew is the same, –30˚ along the vertical axis, this skewed rectangle must then be rotated clockwise by 60˚. Rotating the rectangle itself leads to a change in orientation of its content, a container must be added and then rotated.

A simple way of creating a top face without resorting to maths is to duplicate the left and right rectangles, skew them in the opposite directions (by inverting the sign, e.g. left face is now skewed by –30˚) and position them against the existing faces to create a diamond shape between the two sets. Now use positioning and scaling to fill this diamond and form the top face, deleting the duplicates when finished. My results led to a scaling factor of 1.16 in the Y direction which I have accounted for by reducing the font-size by the same factor.

.topFace div {
	-webkit-transform: skewY(-30deg) scaleY(1.16);
	-moz-transform: skewY(-30deg) scaleY(1.16);
	background-color: #eee;
	font-size: 0.862em;
}

.topFace {
	-webkit-transform: rotate(60deg);
	-moz-transform: rotate(60deg);
	top: -158px;
	left: 100px;
}

The final CSS looks like this:

.cube {
	position: relative;
	top: 200px;
}

.rightFace,
.leftFace,
.topFace div {
	padding: 10px;
	width: 180px;
	height: 180px;
}

.rightFace,
.leftFace,
.topFace {
	position: absolute;
}

.leftFace {
	-webkit-transform: skewY(30deg);
	-moz-transform: skewY(30deg);
	background-color: #ccc;
}

.rightFace {
	-webkit-transform: skewY(-30deg);
	-moz-transform: skewY(-30deg);
	background-color: #ddd;
	left: 200px;
}

.topFace div {
	-webkit-transform: skewY(-30deg) scaleY(1.16);
	-moz-transform: skewY(-30deg) scaleY(1.16);
	background-color: #eee;
	font-size: 0.862em;
}

.topFace {
	-webkit-transform: rotate(60deg);
	-moz-transform: rotate(60deg);
	top: -158px;
	left: 100px;
}

Result

Experiment: Auto-scrolling CSS3 Parallax Effect
Experiment works in Safari 4 Beta and Google Chrome. No JavaScript necessary.

How To

The HTML markup is fairly simple, one DIV for the background and another for the content, the example uses CSS3’s multiple backgrounds, so no need for extra markup to accommodate all those other images:

<div id="background"></div>
<div id="content">
	Content
</div>

For the CSS the background container is set to a fixed position (for convenience more than anything) and spread across the bottom of the page using the top, left, bottom and right properties. The background images are defined using the background shorthand property with multiple declarations being comma delimited, the first being the top-most. Each of the images has a different position defined in percentage, so as the size of the container changes (e.g. on window resize) the images move disproportionately to each other; creating the impressive parallax effect.

#background {
	background: url('../images/foreground.png') 5% 5%,
		url('../images/midground.png') 20% 20%,
		url('../images/background.png') 90% 110%;
}

Ordinarily this effect is only seen when the page is re-sized or JavaScript is used for animation. My first approach to animation via CSS was to apply the transition to the background-positions, with background-position being an animatable property as defined in the proposed specification. However this doesn’t yet work in the latest WebKit nightly build (r42142), it is a known bug.

As an alternate route, albeit a temporary one, I have opted to use transitions to animate the left-most edge of the background container (for instance from 0px to –100px). This gradually alters the overall width of the container causing the backgrounds to shift disproportionately as per their percentages, creating the parallax effect. With a large enough duration and left position the effect appears to be continuous.

#background {
	left: 0;
	-webkit-transition: left 300s linear;
}

#experiment:target #background {
	left: -5000px;
}

To make things a bit more fun I’ve increased the ‘flying speed’ when the mouse hovers over the background area. The final CSS looks like this:

#background {
	background: url('../images/foreground.png') 5% 5%,
		url('../images/midground.png') 20% 20%,
		url('../images/background.png') 90% 110%;
	top: 218px;
	left: 0;
	right: 0;
	bottom: 0;
	position: fixed;
	-webkit-transition: left 300s linear;
}

#experiment:target #background {
	left: -5000px;
}

#experiment:hover #background {
	left: -9999px;
}

Result

Experiment: CSS Analogue Clock
Experiment works in Safari 4 Beta and Google Chrome. A working clock that optionally resorts to JavaScript to grab the current time (can be achieved by other means).

How To

Before getting into the nitty gritty I created four images, a clock face and three transparent PNG hands (seconds, minutes and hours), ensuring that each of these were the same size so that when overlayed their centres would align. The HTML and CSS to get us going is as follows:

<div id="clock">
	<div id="hour"><img src="images/hourHand.png" /></div>
	<div id="minute"><img src="images/minuteHand.png" /></div>
	<div id="second"><img src="images/secondHand.png" /></div>
</div>

#clock {
position: relative;
width: 378px;
height: 378px;
background-image: url('../images/clockFace.png');
left: 50%;
margin: 5em 0 0 -189px;
}

#clock div {
position: absolute;
}

The magic that rotates the clock’s hands comes via two WebKit specific CSS properties, -webkit-transition (documentation) and -webkit-transform (documentation). The transform property can alter the appearance of an element via a two dimensional transformation, for instance: scaling, rotating and skewing a DIV element. In this case it is used to rotate the clock hands to the correct angles; the CSS below puts the hour hand at 3 o’clock:

#clock img[src*='hour'] {
-webkit-transform: rotate(90deg);
}

The transition property creates an animation of a specified property between two values when triggered, for instance fading the opacity on a DIV element from 1 to 0 — triggered using the :hover pseudo class. Transition duration and the transition timing function (e.g. linear) should also be set, amongst other optional properties. In this example the transition is from one transformation angle to another with durations that match the appropriate clock hand, so the second hand takes 60 seconds to complete a 360 degree rotation. The transition is triggered using the :target pseudo element — if the URI contains the ‘clock’ fragment then the time piece shall start ticking.

#clock img[src*='second'] {
/* -webkit-transition: property duration timing-function */
-webkit-transition: -webkit-transform 60s linear;
}

#clock:target img[src*='second'] {
-webkit-transform: rotate(360deg);
}

The above transition lasts only one rotation but by altering the duration length and degree of rotation in accordance the second hand can keep on going (e.g. 600 seconds and 3600 degrees rotation gives a battery life of 10 minutes), a fairly safe assumption that users will not stay on the page for too long.

#clock img[src*='second'] {
-webkit-transition: -webkit-transform 600000s linear;
}

#clock:target img[src*='second'] {
-webkit-transform: rotate(3600000deg);
}

#clock img[src*='minute'] {
-webkit-transition: -webkit-transform 360000s linear;
}

#clock:target img[src*='minute'] {
-webkit-transform: rotate(36000deg);
}

Grab the current time

Although the animation works beautifully, CSS alone is not capable of obtaining the current time. To start the clock at the correct time a dynamic transformation needs to be applied to the clock hand containers, this is easiest done with inline styles and can be set in any number of ways by the backend when the page loads, thereby eradicating any need for JavaScript.

Alternatively, if you’ve no objections to using JavaScript, I’ve created a small startClock() function to do the job (albeit using Prototype 1.6.0.3 for my own convenience):

function startClock() {
	var angle = 360/60;
	var date = new Date();
	var hour = date.getHours();
	if(hour > 12) {
		hour = hour - 12;
	}
	var minute = date.getMinutes();
	var second = date.getSeconds();
	var hourAngle = (360/12)*hour + (360/(12*60))*minute;
	$('minute').setStyle('-webkit-transform: rotate('+angle*minute+'deg)');
	$('second').setStyle('-webkit-transform: rotate('+angle*second+'deg)');
	$('hour').setStyle('-webkit-transform: rotate('+hourAngle+'deg)');
}

A word of warning — applying the inline style directly to the image will override the transition effects defined in the CSS file.