HTML：
去顶部
CSS：
.fl{
display:block;
float:left;
width:50px;
height:50px;
text-align:center;
background-color:#eaeaea;
background-image:url(../images/toTop.png);
}
.fl:hover{background-color:#f442;background-image:url(../images/toTop.png);}
#Fixed {
position: fixed;
_position: absolute;
z-index: 100;
bottom: 70px;
left: 50%;
margin-left: 530px;
_bottom: auto;_top:
expression(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight-70);
width: 50px;
text-indent: -40000px;
background: #fff
}
/*置顶 end*/
Js：