<!doctype html>
<meta charset="utf-8">
<link rel="stylesheet" href="support/highlights.css">
<style>
    * {
        text-decoration-skip-ink: none;
        text-decoration-skip: none;
    }
    main {
        font-size: 7em;
        margin: 0.5em;
        width: min-content;
        text-decoration: 0.125em currentColor solid underline;
        /* try to keep decoration between ascent and baseline */
        text-underline-offset: -0.5em;
    }
</style>
<p>Test passes if there is a solid line through the “O” below.
<main class="highlight_reftest">O</main>