button#back-to-top{max-width:24.5rem;position:fixed;right:50%;bottom:30px;bottom:calc(30px + env(safe-area-inset-bottom));margin-bottom:0;opacity:0;visibility:hidden;transform:translate(50%, 20px);transition:all .3s ease-in-out}button#back-to-top.show{opacity:1;visibility:visible;transform:translate(50%, 0)}