css/css-scroll-snap/scroll-snap-root-001-ref.html

<!DOCTYPE html>
<html>
<title>CSS Scroll Snap Reference</title>
<style>
html, body { margin: 0; padding: 0; }

:root {
  overflow: hidden; /* hide scrollbars for reftest analysis */
}

#target {
  position: absolute;
  top: 25%;
  width: 100%;
  margin: 25vh 0;
  border-top: solid blue;
}
</style>

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