#backtotop{position:fixed;bottom:40px;right:40px;z-index:9999;width:32px;height:32px;text-align:center;line-height:30px;background:#c5c5c5;color:#444;cursor:pointer;border:0;border-radius:2px;text-decoration:none;transition:opacity .2s ease-out;opacity:0}#backtotop:hover{background:#e9ebec}#backtotop.show{opacity:1}