inline-cache-base-uri-cssom.html

<!doctype html>
<title>Relative URI in potentially-cached stylesheet</title>
<link rel="help" href="https://drafts.csswg.org/css-values-4/#relative-urls">
<link rel="match" href="inline-cache-base-uri-cssom-ref.html">
<style>
  :root { background-color: red; }
</style>
<base href="/images/">
<style>
  :root { background-color: red; }
</style>
<script>
document.styleSheets[1].insertRule(`:root { background-image: url(green.png) }`);
</script>