JSFiddle - React, Tailwind, and code Playground

HTML

<figure>
    <div class="a">
        A
    </div>
    <div class="b">
        B
    </div>
</figure>

CSS

.a {
    width: 100px;
    height: 100px;
    background: red;
}

.b {
    width: 100px;
    height: 100px;
    background: blue;
}

.a:hover ~ .b {
    background: green;
}

.b:hover ~ .a {
    background: green;
}