<!DOCTYPE html>
<html class="reftest-wait">
<title>Add background-attachment:fixed during smooth scroll</title>
<link rel="help" href="https://drafts.csswg.org/cssom-view/#dictdef-scrolltooptions">
<link rel="match" href="add-background-attachment-fixed-during-smooth-scroll-ref.html">
<script src="/common/reftest-wait.js"></script>
<style>
#container {
  width: 200px;
  height: 200px;
  overflow: scroll;
  background: linear-gradient(green, blue);
  will-change: transform;
}
#content {
  width: 7500px;
  height: 7500px;
}
</style>
<script>
function startSmoothScroll() {
  var scrollToOptions = {behavior: "smooth", top: 6000};
  container.scrollTo(scrollToOptions);
  requestAnimationFrame(preventCompositedScrolling);
}

function preventCompositedScrolling() {
  container.style.backgroundAttachment = "fixed";
  requestAnimationFrame(waitForSmoothScrollEnd);
}

function waitForSmoothScrollEnd() {
  if (container.scrollTop == 6000) {
    takeScreenshot();
  } else {
    window.requestAnimationFrame(waitForSmoothScrollEnd);
  }
}

onload = () => {
  requestAnimationFrame(startSmoothScroll);
}
</script>
<div id="container">
  <div id="content">Content</div>
</div>