JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <button id="captureStyles">Capture Styles</button>
</body>

CSS

body {
    background-color:red;
}

JavaScript

$(function () {
    $('button#captureStyles').click(function () {
        console.log($(document.body).css('background-color'));
    });
});