ebkit-flex;
    display: flex;
    -webkit-flex: 1;
    flex: 1;
    -webkit-flex-direction: column;
    flex-direction: column;
    -webkit-justify-content: center;
    justify-content: center;
    padding: 1em;
  }

  @media all and (orientation: portrait) {
    body {
      -webkit-flex-direction: column;
      flex-direction: column;
    }
  }
  </style>

  <script>
  var stage;

  window.addEventListener('load', function() {
    stage = document.querySelector('#stage');
    var checkboxSelectionWraps =