css/css-scroll-anchoring/scroll-padding-affects-anchoring.html

<!DOCTYPE html>
<title>scroll anchoring accounts for scroll-padding</title>
<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
<link rel="author" href="https://mozilla.org" title="Mozilla">
<link rel="help" href="https://drafts.csswg.org/css-scroll-anchoring/#anchor-node-selection">
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1/#optimal-viewing-region">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  #scroller {
    overflow: auto;
    height: 500px;
    scroll-padding-top: 200px;
  }
  #changer {
    height: 100px;
  }
  #content {
    height: 1000px;
  }
</style>
<div id="scroller">
  <div id="changer"></div>
  <div id="content"></div>
</div>
<script>
  test(() => {
    scroller.scrollTop = 50;
    changer.style.height = "200px";
    assert_equals(scroller.scrollTop, 150, "Shouldn't anchor to #changer, since it's covered by scroll-padding");
  });
</script>