绝对居中对齐

IE7 及以下不支持

by ipoly

HTML

<div id="cm"></div>

CSS

#cm {
    border: 1px solid red;
    position: absolute;
    margin: auto;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    width: 100px;
    height: 50px;
    
}