css/css-contain/contain-layout-flexbox-001.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Containment Test: Layout containment on flexbox container</title>
<link rel="author" title="Manuel Rego Casasnovas" href="mailto:rego@igalia.com">
<link rel="help" href="https://drafts.csswg.org/css-contain-1/#containment-layout">
<link rel="match" href="reference/contain-layout-flexbox-001-ref.html">
<meta name=assert content="Layout containment does apply to flexbox containers, thus their baseline is the same than if they don't have contents.">
<style>
div {
  display: inline-flex;
  border: 5px solid green;
  contain: layout;
  color: transparent;
  width: 0;
  height: 0;
}
</style>

<p>This test passes if it has the same output as the reference. You see the word "before", a 10px green square at the bottom, and then the word "after".</p>
before<div>f</div>after