.back-to-top{position:fixed;bottom:20px;left:20px;opacity:.5;background-color:transparent;border:1px solid #fff;border-radius:3px;padding:10px 20px;cursor:pointer;transition:all .25s ease-in-out}.back-to-top img{transform:rotate(-90deg);vertical-align:middle}.back-to-top:hover{opacity:1}