.backtotop { width: 38px; height: 38px;border-radius: 20px; line-height: 38px; font-size: 12px; overflow: hidden; z-index: 99999;position: fixed; bottom: 80px; right: 25px; background:#76d1b7;opacity: .6; cursor: pointer;}
.backtotop a { display: block; width: 17px; height:38px; line-height:38px;margin:0 auto;background: url("../images/returntop.png") 0px 13px no-repeat;background-size: 17px 10px; text-indent: -9999px; text-decoration: none; }