<html>
<style>
body {
background-color: white;
}

iframe {
border: 2px solid black;
}
</style>
<script>
window.parent.setupWindow(window);
</script>
<body onload="window.setupBody();">
    <iframe id="middle-child-1" src="frame-tab-focus-child.html"></iframe>
    <iframe id="middle-child-2" src="frame-tab-focus-child.html"></iframe>
</body>
</html>