<!DOCTYPE html>
<html>
<head>
<style type="text/css">
header {
position: absolute;
top: 20px;
width: 200px;
height: 50px;
background-color: silver;
will-change: transform;
}
header.hidden {
visibility: hidden;
}
nav {
height: 37px;
overflow: hidden;
}
nav ul li {
height: 50px;
float: left;
overflow: hidden;
}
</style>
<script type="text/javascript">
if (window.testRunner)
testRunner.dumpAsText();
function doTest() {
var header = document.getElementsByTagName('header')[0];
header.classList.toggle('hidden');
if (window.testRunner && window.internals)
document.getElementById('layertree').innerText = internals.layerTreeAsText(document);
}
window.addEventListener('load', doTest, false);
</script>
</head>
<body>
<header>
<nav>
<ul>
<li>Some text here</li>
</ul>
</nav>
</header>
<pre id="layertree"></pre>
</body>
</html>