   background: #f8f9fa;
            border-radius: 8px;
            border-left: 4px solid #007bff;
        }
        .message-sender {
            font-weight: bold;
            color: #007bff;
            margin-bottom: 5px;
        }
        .message-text {
            margin-bottom: 5px;
        }
        .message-timestamp {
            font-size: 0.85em;
            color: #666;
        }
        .empty-message {
            text-align: center;
            color: #666;
            padding: 40px;
     