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