JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="element"></div>
</div>
<div id="result"></div>

CSS

#container {
    width: 100px;
    height: 100px;
    border: 1px solid black; 
    padding: 2px;
}
#element {
    width: 10%;
    margin: auto 10% 2em 5px;
    padding: 10%;
    height: 10%; 
    background: green;
    border: 1em solid black;
}

JavaScript

function css( el, name ){
    document.getElementById('result').innerHTML += window.getComputedStyle(el, null).getPropertyValue(name) + "<br>";
}

var el = document.getElementById('element');

css(el, 'margin-top');
css(el, 'margin-right');
css(el, 'margin-bottom');
css(el, 'margin-left');