<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<title>Scrolled blend mode</title>

<style>

body {
  margin: 0;
  padding: 100px;
  height: 4000px;
  background: white;
}

#inner-contents {
  border: 1px solid black;
  box-sizing: border-box;
  width: 50px;
  height: 50px;
  margin-top: 1400px;
}

</style>

<div id="inner-contents"></div>

<script>

document.documentElement.scrollTop = 1200;

</script>