overlap-negative-z-index.html | Explore in Territory

<!DOCTYPE html>
<html>
<head>
<style>

  .composited {
    will-change:transform;
  }

  .box {
    width: 100px;
    height: 100px;
  }

  .red {
    background-color: red;
  }

  .lime {
    background-color: lime;
  }

  .behind {
    z-index: -2;
    position: absolute;
    top: 100px;
    left: 100px;
  }

  .ontop {
    z-index: -1;
    position: absolute;
    top: 100px;
    left: 100px;
  }

  #layertree {
    position: absolute;
    left: 10000px;
    top: 0px;
  }

  body {
    overflow: hidden;
  }

</style>
<script>
    if (window.testRunner)
        testRunner.waitUntilDone();

    window.addEventListener('load', function() {
        if (window.testRunner) {
            document.getElementById("layertree").innerText = internals.layerTreeAsText(document);
            testRunner.notifyDone();
        }
    }, false);
</script>

</head>

<body>
  <!-- This red div should be completely underneath the green div -->
  <div class="composited red box behind"> </div>

  <!-- This lime colored div should correctly detect overlap and become composited. -->
  <div class="lime box ontop"> </div>

  <pre id="layertree"></pre>
</body>

</html>

chromium/third_party/blink/web_tests/compositing/layer-creation/overlap-negative-z-index.html