<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<style>
*{
margin: 0;padding: 0;
}
body{ margin:0; padding:10px;}
#head{ margin-bottom:10px; height:50px; background-color:#999999}
#main{}
#left{ width:200px; float:left;margin-right:-200px; background-color:#FF9900}
#mid{ width:auto;background:#00FF00;margin:0 220px;border:1px solid #000;}
#right{ width:200px;margin-left:-200px; float:right; background-color:#CCCC00}
#foot{ margin-top:10px; clear:both; height:50px; background-color:#CCCCCC}
</style>
</head>
<body>
<div id="head">我是头部</div>
<div id="main">
<div id="left">我是左边,宽:200px</div>
<div id="right">我是右边,宽:200px</div>
<div id="mid">我是中间,宽自适应</div>
</div>
<div id="foot">我是底部</div>
</body>
</html>
原文：http://www.cnblogs.com/zhanjiong/p/5732582.html