css/css-grid/grid-items/grid-inline-z-axis-ordering-overlapped-items-006.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Grid Layout Test: 'z-index' property controls the grid items stacking order within an inline grid</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/grid-filled-blue-yellow-green-overlapped-100px-squares.html">
<meta name="flags" content="ahem">
<style>
  #inline-grid {
    display: inline-grid;
    font: 100px/1 Ahem;
    grid-template-columns: 25px 25px 25px 25px;
    grid-template-rows: 25px 25px 25px 25px;
  }

  #blue {
    color: blue;
    z-index: -1;
    grid-column: 2;
    grid-row: 2;
    margin-top: -25px;
    margin-left: -25px;
  }

  #yellow {
    color: yellow;
    grid-column: 4;
    grid-row: 4;
    margin-top: -50px;
    margin-left: -50px;
  }

  #green {
    color: green;
    z-index: 1;
    grid-column: 1;
    grid-row: 1;
    margin-top: 50px;
    margin-left: 50px;
  }
</style>
<p>Test passes if there are 3 filled squares with the same size, and <strong>green</strong> is overlapping <strong>yellow</strong> which is overlapping <strong>blue</strong>.</p>

<div id="inline-grid">
  <div id="green">G</div>
  <div id="yellow">Y</div>
  <div id="blue">B</div>
</div>