JSFiddle - React, Tailwind, and code Playground

HTML

<div> foo </div>
<div> bar </div>

CSS

div { background-color:red; height:100px; margin-bottom:25%; }

JavaScript

var div = $('div').first();

alert( 
    'BODY height: ' + $('body').width() +
    ' .... margin-bottom: ' + div.css('margin-bottom')
);