/*
 
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;
}