<!DOCTYPE html>
<html>
<head>
<title>CSS rem measure</title>
<style type="text/css">
:root {
font-size: 3rem; // 3x size of default paragraph font
}
div {
width: 400px;
height: 130px;
border: 1px solid #FF0000;
}
</style>
</head>
<body>
<div>
<p>First paragraph text.</p>
</div>
</body>
</html>
