CSS绝对定位

by Dong Shelton

HTML

<div class="vertical">
  <div class="content"></div>
</div>

CSS

.vertical {
	position: relative;
	width: 200px;
	height: 200px;
	margin: 0 auto;
	margin-top: 10px;
	border: 1px solid blue;
}
.content {
	position: absolute;
	width: 50px;
	height: 50px;
	background-color: red;
	margin: auto;
	left: 0;
	right: 0;
	top: 0;
	bottom: 0;
}