让IE下支持固定定位
<!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" />
<title>无标题文档</title>
<style>
body {
_background-image: url(null); /*空背景*/
/*_background-image: url(about:blank);*/
_background-attachment: fixed; /* 固定背景 */
} #fixed {
position: fixed;
top: 50%; /* 非IE下的定位 */
_position: absolute; /*IE6 用absolute模拟fixed*/
_top: expression(document.documentElement.scrollTop + Math.round (
document.documentElement.offsetHeight/ 2)+ "px"); /*IE6 动态top值*/
right: 0;
width: 30px;
height: 100px;
margin-top: -50px;
background: #F30;
}
</style>
</head>
<body style="height: 3000px;">
<div id="fixed"></div>
</body>
</html>
<style>
.box{height:2000px;}
.div{width:100px;height:100px;background:red; position:fixed;left:100px;top:100px; _position:absolute;_top:expression(eval(document.documentElement.scrollTop+100));
}
</style>
</head>
<body>
<div class="box">
<div class="div"></div>
</div>