message: chore(codesandbox): avoid FOUC
  This change alleviates FOUC that is sometimes seen in our basic
  CodeSandbox example.
diff: @@ -19,6 +19,16 @@ LICENSE file in the root directory of this source tree.
  #app {
  width: 300px;
  }
  +
  + bx-dropdown,
  + bx-dropdown-item {
  + visibility: hidden;
  + }
  +
  + bx-dropdown:defined,
  + bx-dropdown-item:defined {
  + visibility: inherit;
  + }
  </style>
  <script src="src/index.js"></script>
  </head>
  