footer占用了main的位置,跑到了left和right的下面
<style type="text/css">
body{ margin:0; padding:0; font-size:30px; color:#fff}
.top{width:100%;background:purple;}
.main{width=100%;background:red;position:relative;}
.left{width:200px;background:blue;position:absolute;left:0px;}
.right{position:absolute;right:0px;margin-left:10px;background:green;}
.foot{width:100%;background:orange;}
</style>
</head>
<body>
<div class="top">top</div>
<div class="main">
<div class="right">right</div>
<div class="left">left</div>
</div>
<div class="foot">foot</div>
</body>结果是这样子的
