回到顶部CSS代码——兼容性良好

HTML：

1. <a href="#"class="backToTop"></a>

CSS:

1. .backToTop {width: 23px; height: 72px; display: block;background: url(../images/backToTop.png) no-repeat 0 0; position:fixed; left: 50%; margin-left: 490px; bottom: 125px; z-index:10000;}
   
2. 
   
3. *html .backToTop {position: absolute; left: 50%; margin-left:500px; z-index: 10000; bottom:auto;top:expression_r(eval_r(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight-125-(parseInt(this.currentStyle.marginTop,10)||0)-(parseInt(this.currentStyle.marginBottom,10)||0)));}

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