body {
	margin: 0;
	padding: 0;
	background: #FFF;
}

#centered {
	width: 300px;
	height: 300px;
	position: absolute;
	top: 50%;
	left: 50%;
	margin-top: -150px;
	margin-left: -150px;
	background: #888;
	border: 1px solid #444;
}