JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <body>
        
        <ul>
            <li><a href="#">Home</a></li>
            <li><a href="#">About</a>
                <ul class="submenu">
                    <li><a href="#">Submenu link 1</a></li>
                    <li><a href="#">Submenu link 2</a></li>
                </ul>
            </li>
           
        
    </body>
</html>

CSS

* {
    padding:0;
    margin:0;
}

ul li { 
    float:left;
    
    list-style:none;
    margin:0;
    padding:5px;
    
    position:relative;
}

ul li .submenu {
    display:none;
    position:absolute;
    left:1px;
    top:22px;
    border:1px solid red;
}

ul li:hover .submenu {
    display:block;
}