<html>
<body>
<p style="color: green">This text should be green if height is at least 30ex .</p>
<div style="display:inline; float:left; height: 30ex; background-color: lightblue;">div of height 30ex</div>
<div style="display:inline; float:left; height: 600px; background-color: lightblue;">div of height 600px</div>
</body>
</html>