定位在下角跟着浏览器滚动的代码，兼容ie6

<style type="text/css">
 #ordernow_btn{
position:fixed;
_position:absolute;
bottom:0;
margin:auto;
_bottom:auto;
width:968px;
_top:expression(eval(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight-(parseInt(this.currentStyle.marginTop,10)||0)-(parseInt(this.currentStyle.marginBottom,10)||0)));
}
#qqchat_btn{
position:fixed;
_position:absolute;
bottom:0;
margin-left:5px;
_bottom:auto;
_top:expression(eval(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight-(parseInt(this.currentStyle.marginTop,10)||0)-(parseInt(this.currentStyle.marginBottom,10)||0)));
}
</style>

 

 

<a href="#zxdg" id="ordernow_btn" style="background-image:url(http://www.baidu.com/img/baidu_sylogo1.gif); background-repeat:no-repeat; background-position:center; margin:0px; padding:0px; display: block; clear: both; float: none; height: 47px; width: 968px; text-align:center; position: fixed; _position:absolute; bottom:0px ! important; z-index:1000;"></a>

<a target="_blank" href="tencent://message/?uin=010000&site=在线咨询&Menu=yes" title="在线咨询" id="qqchat_btn"><img src="images/QQchat.gif" /></a>