.to-top{position:fixed;display:inline-block}.fst{position:relative;z-index:999}.fst .to-top{visibility:hidden;opacity:0;transition:opacity 0.3s,visibility 0.3s,background-color 0.3s}.fst .to-top--is-visible{visibility:visible;opacity:1}.fst .to-top:hover{opacity:1}