JSFiddle - React, Tailwind, and code Playground

HTML

<div style="height:100px; border:solid 1px black; overflow-y:scroll; position: relative">
    Please scroll down...
    <br/>
    <div style="height:400px;">
    </div>
    <br/>
    <div id="MrBlue" style="height:20px; background-color:blue; color:white">
        Mr. Blue
    </div>
</div>

<button onclick="alert(document.getElementById('MrBlue').offsetTop)">click me</div>