.top{height:50px;background:grey;}

.main{background:red;width:100%;height:300px;postion:relative;}

.left{width:200px;height:300px;position:absolute;top:50px;background:blue;

}

.right{background:green;postion:absolute;margin-left:210px;height:300px;}

.foot{margin:0 auto;background:pink;clear:both;}