.spinner {
    width: 48px; height: 48px; border: 3px solid rgba(255, 255, 255, 0.3);
    border-top-color: #ffffff; border-radius: 50%; animation: spin 1s linear infinite;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}