css/css-fonts/font-size-zero-1.html

<!DOCTYPE HTML>
<title>CSS Test: font-size: 0</title>
<link rel="author" title="L. David Baron" href="https://dbaron.org/">
<link rel="author" title="Mozilla" href="http://www.mozilla.org/">
<link rel="help" href="http://www.w3.org/TR/css3-fonts/#font-size-prop">
<link rel="help" href="http://www.w3.org/TR/CSS21/box.html#collapsing-margins">
<link rel="match" href="font-size-zero-1-ref.html">
<style>
/* spec ambiguous whether font-size-adjust influences line-height: normal */
body { line-height: 1.2 }

p { margin: 1em 0 }
p.zero { font-size: 0 }
</style>

<p>before</p>
<p class="zero">zero</p>
<p>after</p>