chromium/third_party/blink/web_tests/external/wpt/css/css-scroll-snap/scroll-snap-root-001.html

<!DOCTYPE html>
<html>
<title>scroll-snap-type + scroll-padding propagates root to viewport</title>
<link rel='author' title='Elika J. Etemad' href='http://fantasai.inkedblade.net/contact'>
<link rel='help' href='https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-type'>
<link rel='help' href='https://drafts.csswg.org/css-scroll-snap-1/#scroll-padding'>
<link rel='match' href='scroll-snap-root-001-ref.html'>
<meta name='assert'
      content="Test passes if scroll snap properties on root are applied to viewport.">

<style type='text/css'>
html, body { margin: 0; padding: 0; }

:root {
  scroll-snap-type: block mandatory;
  scroll-padding: 25%;
  overflow: hidden; /* hide scrollbars for reftest analysis */
}

#fail {
  font: bold 2em;
  background: red;
  height: 120vh;
  margin-bottom: 60vh;
}

#target {
  margin-bottom: 120vh;
  scroll-margin: 25vh;
  scroll-snap-align: start;
  border-top: solid blue;
}
</style>

<div id="fail">FAIL</div>

<div id="target">
  <div>Test passes if the blue line above is centered in the viewport.</div>
</div>

<script>
  document.getElementById('target').scrollIntoView();
</script>