JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>fnord
        <ul>
            <li>baz</li>
            <li>foo
                <ul>
                    <li>baz</li>
                    <li>foo</li>
                </ul>
            </li>
        </ul>
    </li>
    <li>gnarf
        <ul>
            <li>baz</li>
            <li>foo
                <ul>
                    <li>baz</li>
                    <li>foo</li>
                </ul>
            </li>
        </ul>
    </li>
</ul>

CSS

li:hover {
    background-color: lightgray;
}

ul li ul li:hover {
    font-weight: bold;
    
}