对于IE7，我们可以利用DIV的"position: fixed;"属性。代码如下：
#ie7_ff{
position: fixed;
top: 0px;
left: 0px;
width: 120px;
}
这段代码对于Firefox浏览器同样适用。但是IE6不支持“position: fixed;”属性。所以针对IE6我们可以用如下代码：
#ie6_ie7{
position: absolute;
width: 120px;
left: 140px;
top: expression(eval(document.documentElement.scrollTop));
}
这段代码对于IE7同样适用。但是FF不支持。
利用浏览器HACK技巧，我们就可以写出兼容IE6，IE7，FF的CSS代码：
#all_f1{
width: 150px;
position: fixed; //IE7，FF
_position: absolute; //IE6
left: 280px;
top: 0px;
_top: expression(eval(document.documentElement.scrollTop)); //IE6
#all_f2{
width: 150px;
position: fixed; //FF
*position: absolute; //IE6，IE7
left: 450px;
top: 0px;
*top: expression(eval(document.documentElement.scrollTop)); // IE6，IE7
----------------------------------------------------------------------------------------------------
<!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>
<title>兼容IE6的淘宝悬浮工具栏</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style type="text/css">
#float{width:744px;height:34px;border:1px solid #C0DBF8;position:absolute;top:0}
#box{position:relative;height:600px;}
</style>
</head>
<body>
<div style="height:300px;background:#eee"></div>
<div id="box"><div id="float" >ddd</div></div>
<div style="height:1000px;background:#eee"></div>
</body>
<script type="text/javascript">
var IO=document.getElementById('float'),Y=IO,H=0,IE6;
IE6=window.ActiveXObject&&!window.XMLHttpRequest;
while(Y){H+=Y.offsetTop;Y=Y.offsetParent};
if(IE6)
IO.style.cssText="position:absolute;top:expression(this.fix?(document"+
".documentElement.scrollTop-(this.javascript||"+H+")):0)";
window.onscroll=function (){
var d=document,s=Math.max(d.documentElement.scrollTop,document.body.scrollTop);
if(s>H&&IO.fix||s<=H&&!IO.fix)return;
if(!IE6)IO.style.position=IO.fix?"":"fixed";
IO.fix=!IO.fix;
};
try{document.execCommand("BackgroundImageCache",false,true)}catch(e){};
//]]>
</script>
</html>