css/css-scroll-anchoring/anchoring-with-bounds-clamping.html

<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>

#changer { height: 1500px; }
#anchor {
  width: 150px;
  height: 4000px;
  background-color: pink;
}

</style>
<div id="changer"></div>
<div id="anchor"></div>
<script>

// Test that scroll anchoring interacts correctly with scroll bounds clamping:
// There should be no visible jump even if the content shrinks such that the
// new max scroll position is less than the previous scroll position.

test(() => {
  document.scrollingElement.scrollTop = 1600;
  document.querySelector("#changer").style.height = "0";
  assert_equals(document.scrollingElement.scrollTop, 100);
}, "Anchoring combined with scroll bounds clamping in the document.");

</script>