Nulla
      facilisi. Proin vitae urna. Quisque dignissim commodo nisl. Curabitur
      bibendum.
    </p>
  </div>

  <div style="clear: both;">
    Zippy 2 sets the expanded state of zippy 3 to the inverted expanded state of
    itself. Hence expanding zippy 2 collapses zippy 3 and vice verse.
  </div>
  <div>
    Zippy 2 and 3 are animated, zippy 1 is not.
  </div>

  <hr>
  <div id="log"></div>
  <script>
    // Set up a logger.
    goog.debug.LogManager.getRoot().setLevel(goog.log.Level.ALL);
    var l