JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="row">
        <article class="span6">
            ...some html text
        </article>
        <aside class="offset3 span3">
            ...some more html text
        </aside>
    </div>
</div>

CSS

[class*="span"]:nth-child(1) {background-color:red;}