<!DOCTYPE html>
<title>Unrelated style mutation does not affect anonymous timeline</title>
<link rel="help" href="https://drafts.csswg.org/scroll-animations-1/#scroll-notation">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/scroll-animations/scroll-timelines/testcommon.js"></script>
<script src="/css/css-animations/support/testcommon.js"></script>
<script src="support/testcommon.js"></script>
<style>
  @keyframes anim {
    from { z-index: 100; }
    to { z-index: 100; }
  }
  #scroller {
    overflow: auto;
    width: 100px;
    height: 100px;
  }
  #element {
    animation: anim forwards;
    animation-timeline: scroll();
  }
  #spacer {
    height: 200px;
  }
</style>
<div id=scroller>
  <div id=element></div>
  <div id=spacer></div>
</div>

<script>
setup(assert_implements_animation_timeline);

promise_test(async () => {
  await waitForCSSScrollTimelineStyle();
  assert_equals(getComputedStyle(element).zIndex, '100');
  // Unrelated style mutation does not change the effect value:
  element.style.color = 'green';
  assert_equals(getComputedStyle(element).zIndex, '100');
});
</script>
