JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="menu">
    <li><a href="#">Home</a></li>
    <li>
        <a href="#">Galleries</a>
        
        <ul>
            <li>Gallery #1</li>
            <li>Gallery #2</li>
        </ul>
    </li>
    <li>
        <a href="#">Albums</a>
        
        <ul>
            <li>Album #1</li>
            <li>Album #2</li>
        </ul>
    </li>
</ul>

CSS

ul.menu li ul {
    display:none;
}

ul.menu li:hover ul {
    display:block;
    position:relative;
}