('button');
      const videoBox = document.querySelector('div');
      const video = document.querySelector('video');

      btn.onclick = function() {
        videoBox.setAttribute('class','showing');
      }

      videoBox.onclick = function() {
        videoBox.setAttribute('class','hidden');
      };

      video.onclick = function() {
        video.play();
      };

    </script>
  </body>
</html>
