e;
            white-space: pre-wrap;
        }

        .response-key {
            color: #d9534f;
            font-weight: bold;
        }

        .response-value {
            color: #5bc0de;
        }
    </style>
</head>
<body>
    <h1>Contact Backend Server</h1>
    <form id="backendForm">
        <label for="action">Action:</label>
        <select id="action" name="action">
            <option value="base64_encode">Base64 Encode</option>
            <option value="md5_hash">MD5 Hash</option>
      