/**
 * 基于绝对定位的解决方案
 */

main {
	position: absolute;
	top: 50%;
	left: 50%;
	margin-top: -3em;
	margin-left: -9em;
	width: 18em;
	height: 6em;
	padding: 1em 1.5em;
	box-sizing: border-box;
	background: #655;
	color: white;
	text-align: center;
}

h1 {
	margin: 0 0 .2em;
	font-size: 150%;
}

p {
	margin: 0;
}

body {
	background: #fb3;
	font: 100%/1.5 sans-serif;
}