<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Overflow: ::scroll-marker with ::scroll-marker-group on root element</title>
<link rel="match" href="root-scroll-marker-ref.html">
<link rel="help" href="https://drafts.csswg.org/css-overflow-5/#scroll-marker-pseudo">
<style>
  body {
    margin: 0;
  }

  :root {
    scroll-marker-group: before;
  }

  :root::scroll-marker-group {
    border: 3px solid black;
    padding: 5px;
    height: 20px;
    display: block;
    position: fixed;
    top: 0;
  }

  div {
    width: 600px;
    height: 300px;
    margin-bottom: 20px;
    background: green;
  }

  div:first-of-type {
    margin-top: 40px;
  }

  div::scroll-marker {
    content: "";
    width: 10px;
    height: 10px;
    background-color: blue;
    border-radius: 100%;
    display: inline-block;
    margin-right: 4px;
  }

  div:last-of-type::scroll-marker {
    margin-right: 0px;
  }
</style>
<div></div>
<div></div>
<div></div>