css/CSS2/stacking-context/composite-change-after-scroll-preserves-stacking-order-ref.html

<!doctype HTML>
<link rel="author" title="Chris Harrelson" href="chrishtr@chromium.org">
<style>
    #one, #two {
        width: 200px; height: 200px; background: lightblue; position: relative
    }
    #one {
        background: lightblue
    }
    #two {
        background: lightgray;
        margin-top: -200px;
    }
</style>
<div id=scroller style="overflow: scroll; width: 300px; height: 300px; will-change: transform">
  <div id=one></div>
  <div id=two></div>
  <div id=spacer style="width: 50px; height: 5000px"></div>
</div>