mozilla-release/layout/reftests/outline/outline-dynamic-change-1a.html

<!DOCTYPE html>
<html class="reftest-wait">
<head>
  <title>
    Test that dynamic tweaks to 'outline-offset' are reflected in the rendering.
  </title>
  <style>
    #tweakMe {
      height: 100px;
      width: 100px;
      background: gray;
      outline: solid 6px black;
      outline-offset: -10px;
    }
  </style>
  <script>
window.addEventListener("MozReftestInvalidate", function() {
  tweakMe.style.outlineOffset = "-16px";
  document.documentElement.removeAttribute("class");
});
  </script>
</head>
<body>
  <div id="tweakMe"></div>
</body>
</html>