mozilla-release/layout/reftests/bugs/18217-zorder-1.html

<!DOCTYPE html>
<html>
<head>
<title>CSS 2.1 Test Suite: Test for z-ordering of inline-table</title>
<link rel="author" title="L. David Baron" href="https://dbaron.org/" />
<link rel="author" title="Mozilla Corporation" href="http://mozilla.com/" />
<link rel="help" href="http://www.w3.org/TR/CSS21/zindex.html#painting-order" />
<meta name="flags" content="" />
<style type="text/css">
div { width: 2em; height: 2em; }
span { display:inline-table; vertical-align: top; width: 2em; height: 2em; background: green; }
div#after { margin-top:-2em; background: red; }
</style>
</head>
<body>
<div><span>&nbsp;</span></div>
<div id="after">&nbsp;</div>
</body>
</html>