JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">

    <div id="block"></div>

</div>

CSS

#container {
    width: 200px;
    height: 200px;
    border: 1px solid black;
}

#block {
    width: 50px;
    height: 50px;
    border: 1px solid red;
    margin: 75px auto;
}

JavaScript

alert($('#block').position().left);