css/css-contain/contain-layout-010.html

<!DOCTYPE html>
<meta charset=utf-8>
<title>CSS Containment Test: Layout containment on table-header-group</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/ref-filled-green-100px-square.xht">
<meta name=flags content="ahem">
<meta name=assert content="Layout containment doesn't apply to table-header-group elements.">

<style>
#wrapper {
  position: relative;
  background: red;
  width: 100px;
  height: 100px;
  padding: 25px;
  box-sizing: border-box;
}
#table-header-group {
  display: table-header-group;
  contain: layout;
}
#abspos {
  position: absolute;
  font: 100px/1 Ahem;
  color: green;
  top: 0;
  left: 0;
}
</style>

<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
<div id="wrapper">
  <div id="table-header-group">
    <div id="abspos">X</div>
  </div>
</div>