JSFiddle - React, Tailwind, and code Playground

HTML

<div class='a'></div>
<div class='b'></div>

CSS

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

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

        .a:hover + .b {
            background: red;
        }