<!DOCTYPE html>
<!-- Any copyright is dedicated to the Public Domain.
   - http://creativecommons.org/publicdomain/zero/1.0/ -->

<html>
  <style>
  details {
    background-color: orange;
    width: 500px;
    height: 200px;
  }
  summary::-moz-list-bullet {
    /* Hide the triangle for comparing with div in reftest. */
    list-style-type: none;
  }
  summary {
    background-color: green;
    width: 50%;
  }
  div#in_summary {
    position: absolute;
    background-color: green;
    top: 60px;
    left: 100px;
    width: 150px;
    height: 100px;
  }
  div#before_summary {
    position: absolute;
    background-color: cyan;
    top: 50px;
    left: 50px;
    width: 150px;
    height: 100px;
  }
  </style>
  <body>
    <details open>
      <div id="before_summary">div before summary</div> <!-- This div is at front. -->
      <summary>Summary<div id="in_summary">div in summary</div></summary>
    </details>
  </body>
</html>