JSFiddle - React, Tailwind, and code Playground

HTML

<div id="menu">
                <ul class="pnav">
                    <li><a href="#">Home</a></li>
                    <li>
                        <a href="#">About GM</a>
                        <ul class="cnav">
                            <li><a href="#">Team</a></li>
                            <li><a href="#">Events</a></li>
                            <li><a href="#">Testimonials</a></li>
                            <li><a href="#">Contact</a></li>
                        </ul>
                    </li>
                    <li><a href="#">Tournaments</a></li>
                    <li><a href="#">Membership</a></li>
                </ul>
            </div>

CSS

ul.pnav {
    list-style: none;
    padding: 0 20px;    
    margin: 0;
    width: 920px;
    background: #222;
    font-size: 1.2em;
    
}
ul.pnav li {
    display:inline;
    margin: 0;  
    padding: 0 15px 0 0;
    position: relative;
}
ul.pnav li a{
    padding: 10px 5px;
    color: #fff;
    text-decoration: none;
}
ul.pnav li a:hover{
    
}

ul.pnav li ul.cnav {
    list-style: none;
    position: absolute; /*--Important - Keeps subnav from affecting main navigation flow--*/
    left: 0; top: 35px;
    background: #333;
    margin: 0; padding: 0;
    display: none;
    width: 170px;
    border: 1px solid #111;
}
ul.pnav li ul.cnav li{
    display:block;
    margin: 0; padding: 0;
    border-top: 1px solid #252525;
    border-bottom: 1px solid #444;
    clear: both;
    width: 170px;
}

JavaScript

$(document).ready(function(){

    //$("ul.cnav").parent().append("<span></span>");

    $("ul.pnav li a").click(function() {

        $(this).parent().find("ul.cnav").slideDown('fast').show();

        $(this).parent().hover(function() {
        }, function(){  
            $(this).parent().find("ul.cnav").slideUp('slow');
        });

    });

});