/* Popup styling */
        #popup {
            display: none;
            position: fixed;
            left: 50%;
            top: 50%;
            transform: translate(-50%, -50%);
            padding: 20px;
            background-color: white;
            border: 1px solid #ccc;
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
        }

        #popup.success { background-color: #d4edda; color: #155724; }
        #popup.error { background-color: #f8d7da; color: #721c24; }

        /* Loading spinner */
        .spinner, .contact-spinner, .subscribe-spinner {
            display: none;
            margin-left: 10px;
        }