mozilla-release/layout/reftests/forms/input/range/moz-range-progress-1-ref.html

<!DOCTYPE html>
<html>
  <head>
    <title>Test ::-moz-range-progress</title>
    <style>

div {
  margin: 0;
  padding: 0;
}

.range {
  display: inline-block;
  position: relative;
  width: 200px;
  height: 20px;
  background-color: blue;
}

.range-progress {
  display: inline-block;
  position: absolute;
  top: 5px;
  width: 50px;
  height: 10px;
  background-color: lime;
}

    </style>
  </head>
  <body>
    <div class="range">
      <div class="range-progress"></div>
    </div>
  </body>
</html>