    </ul>
  </div>
  
  <script>
    // Show/hide platform selector based on message type
    document.getElementById('messageTarget').addEventListener('change', function() {
      const isExtContent = this.value === 'extContent';
      document.getElementById('platformSelector').style.display = isExtContent ? 'block' : 'none';
      document.getElementById('senderName').style.display = isExtContent ? 'block' : 'none';
      document.getElementById('senderNameLabel').style.display = isExtContent ? 