#back-to-top_button{border-radius:4px;bottom:100px;display:inline-block;height:50px;opacity:0;position:fixed;right:22px;text-align:center;transition:background-color .3s,opacity .5s,visibility .5s;visibility:hidden;width:50px;z-index:1000}#back-to-top_button.show{opacity:1;visibility:visible}#back-to-top_button svg{display:inline-block;height:22px;left:50%;margin:0;position:absolute;top:50%;transform:translate(-50%,-50%);width:22px;fill:#fff}