<!-- BEGIN COPY / PASTE -->
    <!-- HTML Structure -->
    <div id="app" class="bg-white text-black">
      <button onclick="toggleTheme()">Toggle Theme</button>
      <p class="p-4">This is a themed paragraph.</p>
    </div>

    <!-- JavaScript for Theme Switching -->
    <script>
      function toggleTheme() {
        const app = document.getElementById('app');
        if (app.classList.contains('bg-white')) {
          app.classList.remove('bg-white', 'text-black');
          app.classList.add('bg-gray-800', 'text-white');
        } else {
          app.classList.remove('bg-gray-800', 'text-white');
          app.classList.add('bg-white', 'text-black');
        }
      }
    </script>
    <!-- END COPY / PASTE -->