css/css-fonts/font-variant-position-04.html

<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8"/>
<title>CSS Test: font-variant-position must synthesize super/subscripts for unsupported characters</title>
<link rel="mismatch" href="font-variant-position-04-notref.html">
<meta name="assert" content="In the case of OpenType fonts that lack subscript or superscript glyphs for a given character, user agents must synthesize appropriate subscript and superscript glyphs">
<link rel="help" href="https://drafts.csswg.org/css-fonts-4/#font-variant-position-prop">

<style>
    /* Lato has superscript Latin letters, but not subscript ones;
     * digits are available in both super- and subscript form.
     */
    @font-face {
        font-family: "lato";
        src: url(/fonts/Lato-Medium.ttf);
    }
    .test {
        font-family: "lato";
        font-size: 2em;
    }
    .sub {
        font-variant-position: sub;
    }
</style>

<section class="test">
    <p>Synthetic subscript letters <em>must</em> be used:</p>
    <p>Text with <span class="sub">subscript</span> letters</p>
</section>