关于兼容性

IE6不支持position:fixed

/*ie6 hack*/
* html, * html body {
background-image: url(about:blank);
background-attachment: fixed;
}

* html #menu {
/*position: fixed;*/
position: absolute;
top: expression(((e=document.documentElement.scrollTop)?e:document.body.scrollTop)+100+'px');
}