<html>
<body>
<p style="color: green">This text should be green if viewport is narrower than 60em.</p>
<div style="width: 60em; background-color: lightblue;">div of length 60 em</div>
<div style="width: 800px; background-color: lightblue;">div of length 800px</div>
</body>
</html>
