JSFiddle - React, Tailwind, and code Playground

HTML

<div class="section-1"><h1>Foo</h1></div>
<h1>Bar</h1>

CSS

:root {
    var-green: #bada55;
}

.section-1 {
    var-blue: #0011ff;
}

h1 {
    color: var(green);
}

.section-1 h1 {
    color: var(blue);
}