css/css-grid/grid-items/grid-z-axis-ordering-004.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Grid Layout Test: 'z-index' property controls the z-axis order of grid items</title>
<link rel="author" title="Manuel Rego Casasnovas" href="mailto:rego@igalia.com">
<link rel="help" href="http://www.w3.org/TR/css-grid-1/#z-order" title="4.4. Z-axis Ordering: the z-index property">
<link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
<meta name="flags" content="ahem">
<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
<style>
  #grid {
    display: grid;
    font: 100px/1 Ahem;
  }

  #test-item-overlapping-green {
    color: green;
    z-index: -5;
  }

  #reference-item-overlapped-red {
    color: red;
    z-index: -10;
  }

  .first-row-first-column {
    grid-area: 1 / 1;
  }
</style>
<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>

<div id="grid">
  <div id="test-item-overlapping-green" class="first-row-first-column">G</div>
  <div id="reference-item-overlapped-red" class="first-row-first-column">R</div>
</div>