stacking-context-overlap.html | Explore in Territory

<!DOCTYPE html>

<html>
<head>
    <style type="text/css" media="screen">
        .trigger {
            width: 20px;
            height: 20px;
            background-color: blue;
            will-change: transform;
        }

        .container {
            position: relative;
            z-index: 0;
            top: -10px;
            height: 120px;
            width: 120px;
            padding: 10px;
            border: 1px solid black;
        }

        .box {
            position: relative;
            height: 100px;
            width: 100px;
            margin: 10px;
            background-color: silver;
        }
    </style>
</head>
<script>
    if (window.testRunner) {
        testRunner.dumpAsText();
        testRunner.waitUntilDone();
    }

    function doTest()
    {
        if (window.testRunner) {
            document.getElementById('layertree').innerText = internals.layerTreeAsText(document);
            testRunner.notifyDone();
        }
    }

    window.addEventListener('load', doTest, false);
</script>
<body>
    <div class="trigger"></div>

    <div class="container">
        <div class="child box">
          <!-- This box doesn't need its own layer. -->
        </div>
    </div>
    <pre id="layertree"></pre>
</body>
</html>

chromium/third_party/blink/web_tests/compositing/layer-creation/stacking-context-overlap.html