[html]<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<style type="text/css">
<!--
body{font-size:12px; color:#999999;}
#nn{width:800px; height:auto; margin:0px auto; border:0px dashed #999999; padding-top:25px;}
#header{height:175px; width:800px;}
#header img{border:1px double #ccc; ; width:200px; float:left;}
#banner{ padding-top:0px; border:1px double #ccc; width:580px;height:30px; float:right;}
#banner p{text-align:right; margin-right:2px;background: #f4f0ed;}
#banner img{border-bottom-width:0px; border-left-width:0px; border-right-width:0px; border-top-width:0px; width:580px;}
#main{width:800px; margin:0px auto;}
#left{width:200px; border:1px dashed #000000; height:450px; clear:both; float:left}
#right1{width:580px; border:1px dashed #000000; height:200px; float:right;}
#right2{width:290px; border:1px dashed #000000; height:250px; float:right;}
#bottom{width:800px; margin:5px auto;float:left;background: #e0d6cd;}
-->
</style>
</head>
<body>
<div id="nn">
<div id="header">第一块
<div id="banner"><p>第二块</p>
</div>
<div id="banner">第三块
</div>
</div>
<div id="main">
<div id="left">第四块
</div>
<div style="clear:none"></div>
<div id="right1">第五块
</div>
<div id="right2">第六块
</div>
<div id="right2">第七块
</div>
</div>
<div id="bottom">2222222222222222222222222222222222222
</div>
</div>
</body>
</html>
请问如何把“第四块”也就是左边栏分拆成多块？
