返回顶部：

a.backtop {          background: url(/coin-portlet/images/backtotop.png) no-repeat center center;          bottom: 20px;          cursor: pointer;          display: none;          height: 70px;          position: fixed;          right: 20px;          text-indent: -9999px;          width: 70px;          z-index: 100; }

function backtopFun() {   $(window).scroll(function() {    if ($(window).scrollTop() >= 200) {    $(".backtop").fadeIn();    } else {    $(".backtop").fadeOut();    }    });   $(".backtop").click(function(event) {    $('html,body').animate({    scrollTop : 0    }, 500);    return false;    });    }   $(function() {    backtopFun();    });