top{width:960px;height:100px;background:#ccc;margin:0 auto;}

.main{width:960px;height:400px;background:#fff;margin:0 auto;}

.left{ width:220px;height:400px;background:blue;float:left;}

.right{width:740px;height:400px;background:green;float:right}

.abc{width:240px;height:400px;background:red;float:left;}

.foot{width:960px;height:100px;background:#000;clear:both;margin:0 auto;}