css/css-scroll-anchoring/exclude-sticky.html

<!DOCTYPE html>
<meta charset="utf-8">
<link rel="help" href="https://drafts.csswg.org/css-scroll-anchoring-1/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>

body { height: 400vh; margin: 0; }
#sticky, #content { width: 200px; height: 100px; }
#sticky { position: sticky; left: 100px; top: 50px; }
#before { height: 50px; }
#content { margin-top: 100px; }

</style>
<div id="sticky">sticky</div>
<div id="before"></div>
<div id="content">content</div>
<script>

// Tests that the anchor selection algorithm skips sticky-positioned elements.

test(() => {
  document.scrollingElement.scrollTop = 150;
  document.querySelector("#before").style.height = "100px";
  assert_equals(document.scrollingElement.scrollTop, 200);
}, "Sticky-positioned headers shouldn't be chosen as scroll anchors (we should use 'content' instead)");

</script>