Jquery 实现banner图滚动效果

/*广告图片切换*/
#focus{width:340px;height:256px;overflow:hidden;position:relative;z-index:1;}
#focus ul{height:400px;position:absolute;}
#focus ul li{float:left;width:340px;height:318px;overflow:hidden; position:relative; background:#fff; }
#focus ul li p{position:absolute; top:233px; left:10px; font-size:12px; color:#ffffff; z-index:99999}
#focus ul li div{position:absolute; overflow:hidden;}
#focus .btnBg{position:absolute;width:800px;height:30px;left:0;bottom:0;background:#000;}
#focus .btn{position:absolute;width:780px;height:10px;padding:10px 10px;*padding:10px 10px;right:0;bottom:0;text-align:right;}
#focus .btn span{display:inline-block;_display:inline;_zoom:1;width:10px;height:10px;_font-size:0;margin-left:5px;cursor:pointer;background:#fff;}
#focus .btn span.on{background:#fff;}
#focus .preNext{width:45px;height:100px;position:absolute;top:90px;background:url(/content/images/sprite.png) no-repeat 0 0;cursor:pointer;}
#focus .pre{left:0;}
#focus .next{right:0;background-position:right top;}
#focus ul,li{list-style:none;}
#focus img{border:0;}
#focus ul li{float:left;width:340px;height:256px;overflow:hidden;position:relative;background:#fff;}