.backtotopbutton{display:inline-block;background-color:silver;width:50px;height:50px;text-align:center;border-radius:4px;position:fixed;bottom:20px;right:20px;transition:background-color .3s,opacity .5s,visibility .5s;opacity:0;visibility:hidden;z-index:1000}.backtotopbutton::after{content:"";font-family:FontAwesome;font-weight:normal;font-style:normal;font-size:2em;line-height:50px;color:#fff}.backtotopbutton:hover{cursor:pointer;background-color:#333}.backtotopbutton:active{background-color:#555}.backtotopbutton.show{opacity:.7;visibility:visible}