<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<style type="text/css">
body{margin: 0;padding: 0;}
.left{width: 200px;height: 500px;background: #aaa;float: left;}
.middle{height: 500px;background: #fff;float: left;}
.right{width: 300px;height: 500px;background: #ccc;float: right;}
</style>
</head>
<body>
<div>1</div>
<div>2</div>
<div>3</div>
</body>
</html>李晓健