iOS 6 style switch checkboxes

dabblet.css

/**
 * iOS 6 style switch checkboxes
 * by Lea Verou http://lea.verou.me
 */

:root input[type="checkbox"] { /* :root here acting as a filter for older browsers */
	position: absolute;
	opacity: 0;
}

:root input[type="checkbox"].ios-switch + div {
	display: inline-block;
	vertical-align: middle;
	width: 3em;	height: 1em;
	border: 1px solid rgba(0,0,0,.3);
	border-radius: 999px;
	margin: 0 .5em;
	background: white;
	background-image: linear-gradient(rgba(0,0,0,.1), transparent),
	                  linear-gradient(90deg, hsl(210, 90%, 60%) 50%, transparent 50%);
	background-size: 200% 100%;
	background-position: 100% 0;
	background-origin: border-box;
	background-clip: border-box;
	overflow: hidden;
	transition-duration: .4s;
	transition-property: padding, width, background-position, text-indent;
	box-shadow: 0 .1em .1em rgba(0,0,0,.2) inset,
	            0 .45em 0 .1em rgba(0,0,0,.05) inset;
	font-size: 150%; /* change this and see how they adjust! */
}

:root input[type="checkbox"].ios-switch:checked + div {
	padding-left: 2em;	width: 1em;
	background-position: 0 0;
}

:root input[type="checkbox"].ios-switch + div:before {
	content: 'On';
	float: left;
	width: 1.65em; height: 1.65em;
	margin: -.1em;
	border: 1px solid rgba(0,0,0,.35);
	border-radius: inherit;
	background: white;
	background-image: linear-gradient(rgba(0,0,0,.2), transparent);
	box-shadow: 0 .1em .1em .1em hsla(0,0%,100%,.8) inset,
	            0 0 .5em rgba(0,0,0,.3);
	color: white;
	text-shadow: 0 -1px 1px rgba(0,0,0,.3);
	text-indent: -2.5em;
}

:root input[type="checkbox"].ios-switch:active + div:before {
	background-color: #eee;
}

:root input[type="checkbox"].ios-switch:focus + div {
	box-shadow: 0 .1em .1em rgba(0,0,0,.2) inset,
	            0 .45em 0 .1em rgba(0,0,0,.05) inset,
	            0 0 .4em 1px rgba(255,0,0,.5);
}

:root input[type="checkbox"].ios-switch + div:before,
:root input[type="checkbox"].ios-switch + div:after {
	font: bold 60%/1.9 sans-serif;
	text-transform: uppercase;
}

:root input[type="checkbox"].ios-switch + div:after {
	content: 'Off';
	float: left;
	text-indent: .5em;
	color: rgba(0,0,0,.45);
	text-shadow: none;

}


/* Switch code ends here, from now on it’s just bling for the demo page */

label {
	position: relative;
	display: block;
	padding: .8em;
	border: 1px solid silver;
	border-top-width: 0;
	background: white;
	font: bold 110% sans-serif;
}

label:first-of-type {
	border-top-width: 1px;
	border-radius: .6em .6em 0 0;
}

label:last-of-type {
	border-radius: 0 0 .6em .6em;
	box-shadow: 0 1px hsla(0,0%,100%,.8);
}

body {
	padding: 1em;
	background: #d2d4dd;
	background-image: linear-gradient(90deg, transparent 30%, rgba(0,0,0,.02) 45%, rgba(0,0,0,.02) 55%, transparent 70%);
	background-size: 8px 8px;
	font: 100%/1.5 sans-serif;
	text-shadow: 0 1px 1px white;
}

dabblet.html

<h1>iOS 6 style switches with pure CSS</h1>

<label>Something <input type="checkbox" class="ios-switch" /></label>
<label>Pre-checked<input type="checkbox" class="ios-switch" checked /></label>

<label><input type="checkbox" class="ios-switch" />Label after control</label>
<label><input type="checkbox" class="ios-switch" checked />Another label after control</label>

<p>Check out the slide animation, even in WebKit versions that don’t support animation for pseudo-elements.
   Verified to work in <strong>Chrome, Firefox, IE10</strong>, but could possibly work in many others.</p>

<ul>
	<li>Keyboard accessible</li>
	<li>No images</li>
	<li>No JS (except a tiny bit to add a div per checkbox, but you can do that manually</li>
	<li>Only one extra element per switch</li>
	<li>Standards compliant: Does not depend on any proprietary stuff</li>
	<li>Degrades gracefully</li>
	<li>Easy to scale by just changing its font-size</li>
</ul>

dabblet.js

// JS is only used to add the <div>s
var switches = document.querySelectorAll('input[type="checkbox"].ios-switch');

for (var i=0, sw; sw = switches[i++]; ) {
	var div = document.createElement('div');
	div.className = 'switch';
	sw.parentNode.insertBefore(div, sw.nextSibling);
}

settings.json

{"view":"split","fontsize":"100","seethrough":"","prefixfree":"1","page":"css"}

TL;DR X_X

This is a grate solution, exactly what I was looking for a project of mine. Can you tell me what license apply to this code?

Suggestion, can you add:

box-sizing: content-box;

to line 12? It doesn't work correctly when box-sizing: border-box is on.