.back-to-top{position:fixed;bottom:40px;right:40px;width:50px;height:50px;border-radius:50%;background:#000;color:#fff;border:1px solid #e0e0e0;cursor:pointer;display:flex;align-items:center;justify-content:center;box-shadow:0 4px 12px #0000001a;transition:all .3s ease;z-index:999;opacity:.9}.back-to-top:hover{opacity:1;transform:translateY(-3px);box-shadow:0 6px 16px #00000026}.back-to-top:active{transform:translateY(-1px)}.back-to-top svg{width:24px;height:24px}[data-theme=dark] .back-to-top{background:#fff;color:#000;border:1px solid #333}@media (max-width:768px){.back-to-top{display:none}}@keyframes fadeInUp{0%{opacity:0;transform:translateY(20px)}to{opacity:.9;transform:translateY(0)}}.back-to-top{animation:fadeInUp .3s ease}