css/css-cascade/scope-implicit-remove-sheet.html

<!DOCTYPE html>
<title>CSS Cascading Test: Invalidate style when implicit @scope sheet is removed</title>
<link rel="help" href="https://drafts.csswg.org/css-cascade-6/#scoped-styles">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="target">
  <style id="scope_sheet">
    @scope { --matches-scope: true; }
  </style>
</div>
<script>
  test(() => {
    assert_equals(getComputedStyle(target).getPropertyValue("--matches-scope"), "true");
  }, "Implicit @scope rule initially matches");

  test(() => {
    scope_sheet.remove();
    assert_equals(getComputedStyle(target).getPropertyValue("--matches-scope"), "");
  }, "@scope rule no longer matches after sheet removal");
</script>