.spinner {
    border: 3px solid rgba(255, 255, 255, 0.2);
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border-top-color: #ffffff;
    animation: spin 1s linear infinite;
    display: inline-block;
}

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

.hidden {
    display: none !important;
}