<!DOCTYPE html>
<html class="reftest-wait">
<title>Basic of anchor-scroll: anchored elements should keep "pinned" to the anchor during anchor scroll updates</title>
<link rel="author" href="mailto:xiaochengh@chromium.org">
<link rel="help" href="https://drafts.csswg.org/css-anchor-1/">
<link rel="match" href="reference/anchor-scroll-ref.html">
<link rel="stylesheet" href="/fonts/ahem.css">
<style>
body {
  font: 20px/1 Ahem;
  margin: 0;
}

#scroll-container {
  width: 400px;
  height: 400px;
  overflow: scroll;
}

#scroll-contents {
  width: 1000px;
  height: 1000px;
  position: relative;
}

#placefiller-above-anchor {
  height: 500px;
}

#placefiller-before-anchor {
  display: inline-block;
  width: 500px;
}

#anchor {
  anchor-name: --anchor;
}

#inner-anchored {
  color: green;
  position: absolute;
  left: anchor(--anchor left);
  bottom: anchor(--anchor top);
  anchor-scroll: --anchor;
}

#outer-anchored {
  color: yellow;
  position: absolute;
  left: anchor(--anchor left);
  top: anchor(--anchor bottom);
  anchor-scroll: --anchor;
}
</style>

<div style="position: relative">
  <div id="scroll-container">
    <div id="scroll-contents">
      <div id="placefiller-above-anchor"></div>
      <div id="placefiller-before-anchor"></div>
      <span id="anchor">anchor</span>
      <div id="inner-anchored">inner-anchored</div>
    </div>
  </div>
  <div id="outer-anchored">outer-anchored</div>
</div>

<script>
function raf() {
  return new Promise(resolve => requestAnimationFrame(resolve));
}

async function runTest() {
  await raf();
  await raf();
  const scroller = document.getElementById('scroll-container');
  scroller.scrollTop = 300;
  scroller.scrollLeft = 450;
  document.documentElement.classList.remove('reftest-wait');
}
runTest();
</script>
</html>
