如下图以及代码，中间那块怎么跑到下面去了
.left{ width:200px; height:600px; background:#ccc;position:position; left:0; top:0;}
.main{ height:600px;margin:0 310px 0 210px; background:#9CF}
.right{ height:600px; width:300px; position:absolute; top:0; right:0; background:#FCC;}
