#wrapper{margin:0 auto;width:900px;position:relative}#back-top{position:fixed;bottom:30px;left:50%;margin-left:500px;z-index:99999999}#back-top a{width:64px;display:block;text-align:center;font:11px/100% arial,helvetica,sans-serif;text-transform:uppercase;text-decoration:none;color:#bbb;-webkit-transition:1s;-moz-transition:1s;transition:1s;opacity:0.3;-moz-opacity:0.3;filter:alpha(opacity=40)}#back-top a:hover{color:#000;opacity:1.0;-moz-opacity:1.0;filter:alpha(opacity=100)}#back-top span{width:132px;height:175px;display:block;margin-bottom:7px;background:url(../up.png) no-repeat center center;-webkit-border-radius:1px;-moz-border-radius:1px;border-radius:1px;-webkit-transition:1s;-moz-transition:1s;transition:1s}}#back-top a:hover{}