JSFiddle - React, Tailwind, and code Playground

HTML

<div class='a'>
    Should be blue
    <div class='b'>
        Should be red
    </div>
</div>

CSS

.a .b:before {
    content: "|Inserted using :before|";
}

.a {
    color: blue;
}
.b {
    color: red;
}