lapped-reference
    {
      background-color: red;
      height: 100px;
      position: relative;
      width: 100px;
      z-index: -1;
    }
  </style>

  <p>Test passes if there is a filled green square and <strong>no red</strong>.

  <div id="green-overlapping-test"></div>

  <div id="red-overlapped-reference"></div>
