.back-to-top { position: fixed; z-index: 45; right: max(24px, env(safe-area-inset-right)); bottom: max(24px, env(safe-area-inset-bottom)); display: grid; place-items: center; width: 44px; height: 44px; padding: 10px; border: 1px solid #dce5ee; border-radius: 12px; background: var(--panel, #fff); color: var(--blue, #2563eb); box-shadow: 0 4px 16px rgba(30, 55, 80, .12); cursor: pointer; transition: background .15s, border-color .15s, box-shadow .15s; touch-action: manipulation; }
.back-to-top[hidden] { display: none; }
.back-to-top svg { display: block; width: 22px; height: 22px; pointer-events: none; }
.back-to-top:hover { border-color: #acc8f7; background: #eff6ff; box-shadow: 0 5px 20px rgba(37, 99, 235, .16); }
.back-to-top:focus-visible { outline: 2px solid var(--blue, #2563eb); outline-offset: 3px; }
@media (max-width: 820px) { .back-to-top { right: max(16px, env(safe-area-inset-right)); bottom: max(16px, env(safe-area-inset-bottom)); } }
@media (prefers-reduced-motion: reduce) { .back-to-top { transition: none; } }