<!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=UTF-8" />
</head>
<style type="text/css">
body{margin:0;padding:0;}
.wrap{990px;margin:0 auto;height:1500px;background:#ccc;}
* html,* html body{background-image:url(about:blank); background-attachment:fixed;}
.ad{100%;position:fixed;_position:absolute;top:110px;left:0;_top:expression(eval(document.documentElement.scrollTop+110));}
.bannerWrap{990px;height:0;position:absolute;top:0;left:50%;margin-left:-495px;}
.ad_left, .ad_right{background:#f00;100px;height:300px;position:relative;}
.ad_left{float:left;left:-105px;}
.ad_right{float:right;right:-105px;}
</style>
<body>
<div class="wrap">
正文内容
<p><a href="#">sdfasdffffffasdfasdf</a></p>
</div>
<div class="ad">
<div class="bannerWrap">
<div class="ad_left">asdfasf</div>
<div class="ad_right">asdfasf</div>
</div>
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</body>
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