<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{
margin:0;
padding:0;
}
.left{
float:left;
width:200px;
height:500px;
background: green;
}
.middle{
width: 100%;
margin-left: -200px;
margin-right: -200px;
background: red;
height:500px;
}
.right{
float:right;
width:200px;
height:500px;
background: green;
position: relative;
top:-500px;
}
</style>
</head>
<body>
<div class="left"></div>
<div class="middle"></div>
<div class="right"></div>
</body>
</html>
原文：http://www.cnblogs.com/qiancheng123/p/6337388.html