.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
    margin-right: 8px;
}

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

button:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}