<!DOCTYPE html>
<html>
<head>
<style>
sub {
vertical-align: sub;
font-size: smaller;
}
</style>
</head>
<body>
<p>A sub element is displayed like this:</p>
<p>This text contains <sub>subscript text</sub></p>
<p>Change the default CSS settings to see the effect.</p>
</body>
</html>