<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Document</title>
<style type="text/css">
body{margin: 0 auto;}
.main{width: 900px;margin: 0 auto;}
.main .left{width: 300px;float: left;}
.main .left div{height: 298px;background: green;border: solid 1px blue;}
.main .center{width: 300px;float: left;}
.main .center div{height: 198px;background: gray;border: solid 1px black;}
.main .right{width: 300px;float: left;}
.main .right div{height: 298px;background: blue;border: solid 1px red;}
</style>
</head>
<body>
<div class="main">
<div class="a"></div>
<div class="left">
<div></div>
<div></div>
</div>
<div class="center">
<div></div>
<div></div>
<div></div>
</div>
<div class="right">
<div></div>
<div></div>
</div>
</div>
</body>
</html>
![]()
