<div id="floatPanel"> 
        <div class="ctrolPanel" style="right:20px;"> 
            <a class="arrow" href="#"><img title="点击回到顶部" src="images/huidao.jpg" /></a> 
        </div> 
    </div>

#floatPanel .ctrolPanel{width:60px;;height:60px;position:fixed;right:25px;top:85%;overflow:hidden;z-index:10000;}