css/css-values/rlh-unit-001.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Values and Units Test: using rlh in calc</title>
<link rel="help" href="https://drafts.csswg.org/css-values-4/#font-relative-lengths">
<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
<meta name="assert" content="The rlh unit resolves against the root when used in calc.">
<style>
  :root {
    line-height: 50px;
  }

  p {
    line-height: normal;
  }

  .container {
    position: relative;
    width: 100px;
    height: 100px;
  }

  .contents {
    position: absolute;
    top: 0;
    left: 0;
  }

  .div1 {
    background-color: green;
    width: 100px;
    height: 100px;
  }

  .div2 {
    line-height: 10px;
    block-size: 100px;
    background-color: red;
    inline-size: calc(1rlh - 1rlh);
  }
</style>

<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>

<div class="container">
  <div class="div1 contents"></div>
  <div class="div2 contents"></div>
</div>