.spinner {
    border: 8px solid rgba(0, 0, 0, 0.1);
    border-left-color: #000;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 0.3s linear infinite;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

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