anchor-scroll-position-try-012.html

<!DOCTYPE html>
<html class="reftest-wait">
<title>Tests position fallback change on scroll with anchor and anchored under the same scroll container</title>
<link rel="help" href="https://drafts.csswg.org/css-anchor-1/#scroll">
<link rel="help" href="https://drafts.csswg.org/css-anchor-1/#fallback">
<link rel="match" href="anchor-scroll-position-try-012-ref.html">
<style>
#scroller {
  position: relative;
  width: 400px;
  height: 400px;
  overflow-y: scroll;
}

.box {
  min-height: 100px;
  width: 100px;
}

#anchor {
  anchor-name: --a;
  background: orange;
}

#anchored {
  position: absolute;
  top: anchor(bottom);
  width: 100px;
  height: 100px;
  background: green;
  position-anchor: --a;
  position-try-fallbacks: --pf;
}

@position-try --pf {
  top: auto;
  bottom: anchor(top);
}
</style>

<div id="scroller">
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box" id="anchor"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div id="anchored"></div>
</div>

<script>
requestAnimationFrame(() => {
  requestAnimationFrame(() => {
    scroller.scrollTop = 150;
    document.documentElement.classList.remove('reftest-wait');
  });
});
</script>
</html>

chromium/third_party/blink/web_tests/external/wpt/css/css-anchor-position/anchor-scroll-position-try-012.html