.back-top{position:fixed;right:10px;top:50%;margin-top:-160px;width:54px;text-align:center;background:#fff;color:#999;z-index:49}.back-top ul{list-style:none;margin:0;padding:0}.back-top ul li{height:80px;border-bottom:1px solid #e3e3e3;cursor:pointer;position:relative}.back-top ul li img{display:inline;margin-top:14px}.back-top ul li img.on{display:none}.back-top ul li p{margin:0;line-height:32px}.back-top ul li .app-two{position:absolute;left:-121px;bottom:0;display:none}.back-top ul li:hover .app-two{display:block}.back-top ul li:hover>img{display:none}.back-top ul li:hover>img.on{display:inline}.back-top ul li:last-child{border-bottom:none}