body { margin: 0; height: 100vh; }

#loader {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    border: 12px solid #f3f3f3;
    border-top: 12px solid #3498db;
    border-radius: 50%;
    width: 80px;
    height: 80px;
    animation: spin 2s linear infinite;
    will-change: transform;
}

@keyframes spin {
    0% { transform: translate(-50%, -50%) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
}