JSFiddle - React, Tailwind, and code Playground

HTML

<div id="an-element">
    <ul>
        <li>One</li>
        <li>Two</li>
    </ul>
</div

CSS

#an-element{
    background: #F00 !important;
}

#an-element{
    background: #0F0 !important;
}

JavaScript

$(function () {  
    $("#an-element").attr('style', 'background: #00F !important;');
});