JSFiddle - React, Tailwind, and code Playground

HTML

<div class="red"></div>

CSS

div{
    width:100px;
    height:100px;
}
.red{background:red;}

JavaScript

$("head").append('<style type="text/css"></style>');
var new_stylesheet = $("head").children(':last');
new_stylesheet.html('.red{background:green;}');