/*

Based on Stu Nicols demo at http://www.cssplay.co.uk/boxes/outside.html

Set the percentage width on the out element and the extra pixels-based width extension on the inner using negative margins

*/

.outside {
	position: relative;
	width: 25%;
	background: #9caf9c;
	color: #fff;
	margin: 1em auto;
}
.inside {
	display: block;
	position: relative;
	color: #000;
	margin: 0 -50px;
	background: #c4c4c4;
	color: #000;
}

Way to specify the width of an element as percentage pixels

css, textmate

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