css/css-scrollbars/viewport-scrollbar-ref.html

<!DOCTYPE html>
<meta charset="UTF-8">
<title>CSS Reference: styled scrollbars</title>
<link rel="author" title="Xidorn Quan" href="https://www.upsuper.org">
<link rel="author" title="Mozilla" href="https://www.mozilla.org">
<link rel="help" href="https://drafts.csswg.org/css-scrollbars-1/#scrollbar-color-properties">
<style>
#outer {
  border: 1px solid black;
  width: 200px; height: 200px;
  overflow: scroll;
  scrollbar-color: yellow blue;
}
#inner {
  width: 400px; height: 400px;
}
</style>
<p>Test passes if the scrollbars in the following box are styled:</p>
<div id="outer">
  <div id="inner">
  </div>
</div>