<!DOCTYPE html>
<script>
onload = () => {
outerDiv.scrollTop = 300;
innerDiv.scrollTop = 400;
}
</script>
<div style="height: 300px; overflow-y: scroll;" id="outerDiv">
<div style="height: 300px;"></div>
<div style="height: 400px; overflow-y: scroll;" id="innerDiv">
<div style="height: 800px; width: 300px; background: green"></div>
</div>
</div>