scroll-animations/css/scroll-timeline-default-iframe-ref.html

<!DOCTYPE html>
<title>Reference for default scroll() timeline</title>
<iframe width="400" height="400" srcdoc='
  <html>
  <style>
    html {
      print-color-adjust: exact;
      min-height: 100%;
      padding-bottom: 100px;
    }

    #box {
      width: 100px;
      height: 100px;
      background-color: green;
      transform: translateY(100px);
    }

    * {
      margin-top: 0px;
      margin-bottom: 0px;
    }
  </style>
  <script>
    window.addEventListener("load", function() {
      // Move the scroller to halfway.
      const scroller = document.scrollingElement;
      const maxScroll = scroller.scrollHeight - scroller.clientHeight;
      scroller.scrollTop = 0.5 * maxScroll;
    });
  </script>
  <div id="box"></div>
  </html>
'></iframe>