<!DOCTYPE html>
<style>
.yellow::first-line { color:grey }
</style>
<body>
<p>Test to make sure that the decoration line paints properly underneath the subscript.
</p>

<p class="yellow" style="font-size:40px; padding-top:5px; float:left; text-decoration:underline;text-underline-position:under; border:1px dotted orange"><span style="position:relative;">Here is the subscript for this line.</span>
</p>
</body>