popup.html

<!DOCTYPE html>
<html>
<head>
  <link rel="stylesheet" href="css/style.css">
  <script src="js/popup.js"></script>
</head>
  <body>
    <p>Alternaterr</p>
    <ul>
      <li class="">Default</li>
      <li class="red" title="Red"></li>
      <li class="green" title="Green"></li>
      <li class="blue" title="Blue"></li>
      <li class="yellow" title="Yellow"></li>
    </ul>
  </body>
</html>