.back-to-top{position:fixed;right:30px;bottom:30px;z-index:40;width:54px;height:54px;min-height:54px;padding:0;border-radius:50%;background:var(--ink);color:var(--paper-light);box-shadow:0 8px 24px -6px rgb(41 38 32 / .32);visibility:hidden;opacity:0}
.back-to-top .icon{width:24px;height:24px}
@media(max-width:640px){.back-to-top{right:18px;bottom:calc(18px + env(safe-area-inset-bottom,0px));width:48px;height:48px;min-height:48px}}