JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrap">
    <div class="a">AAAA
    <div class ="b">BBBB</div>
    </div>
</div>

CSS

.a {
    color: red;
}

.b {
    color: orange;
}

.b:hover .a {
    background-color: blue;
}