ference-overlapped-red {
    position: absolute;
    background-color: red;
    width: 100px;
    height: 100px;
    z-index: -1;
  }

  #constrained-grid {
    display: grid;
    width: 10px;
    height: 10px;
  }
</style>
<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>

<div id="reference-overlapped-red"></div>
<div id="constrained-grid">
  <img src="support/100x100-green.png" alt="Image download support must be enabled" />
</div>

