text: // This page should only be loaded by older browsers
  // that don't support <script type="module">.
  
  // Validates with [jshint]
  (function() {
      'use strict';
      document.addEventListener('DOMContentLoaded', function() {
          // Show warning element. The text content is initially
          // stored in the attribute [data-content] so that bots
          // which read the page do include it as content text.
          var warning = document.getElementById('old-browser-warning');
          var content = warning.querySelector('[data-content]');
          content.textContent = content.getAttribute('data-content');
          warning.removeAttribute('hidden');
  
          // Disable buttons
          var buttons = document.querySelectorAll('button');
          Array.prototype.forEach.call(buttons, function(button) {
              button.disabled = true;
          });
      });
  })();