<!DOCTYPE html>
<html>
<head>

<meta name="viewport" content="width=800">
<style>
html { font-size: 16px; }
body { width: 800px; margin: 0; overflow-y: hidden; }
</style>

</head>
<body>

<div style="width: 600px; overflow: hidden; font-size: 2.5rem">
    This text should be autosized to 40px computed font size (16 * 800/320), since the overflow:hidden does not cause this to be a new cluster, so it is part of the 800px wide root cluster.
</div>

<div style="font-size: 2.5rem">
    This text should similarly be autosized to 40px.<br>
    Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
</div>

</body>
</html>