JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
<html>
<head>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
</head>
    <ul id="nav">
    <li><a href="#">Parent 01</a></li>
    <li><a href="#" class="selected">Parent 02</a>
        <ul>
            <li><a href="#">Item 01</a></li>
            <li><a href="#" class="selected">Item 02</a></li>
            <li><a href="#">Item 03</a></li>
        </ul>
        <div class="clear"></div>
    </li>
    <li><a href="#">Parent 03</a>
    <ul>
        <li><a href="#">Item 04</a></li>
        <li><a href="#">Item 05</a></li>
        <li><a href="#">Item 06</a></li>
        <li><a href="#">Item 07</a></li>
    </ul>        
        <div class="clear"></div>
    </li>
    <li><a href="#">Parent 04</a></li>
</ul>
 
<div class="clear"></div>
</html>

CSS

body {font-family:arial; font-size:11px;}
.clear {clear:both}
/* remove the list style */
#nav {
    margin:0;
    padding:0;
    list-style:none;
}  
     
    /* make the LI display inline */
    /* it's position relative so that position absolute */
    /* can be used in submenu */
    #nav li {
        float:left;
        display:block;
        width:100px;
        background:#ccc;
        position:relative;
        z-index:500;
        margin:0 1px;
    }
         
    /* this is the parent menu */
    #nav li a {
        display:block;
        padding:8px 5px 0 5px;
        font-weight:700; 
        height:23px;
        text-decoration:none;
        color:#fff;
        text-align:center;
        color:#333;
    }
 
    #nav li a:hover {
        color:#fff;
    }
     
    /* you can make a different style for default selected value */
    #nav a.selected {
        color:#f00;
    }
     
        /* submenu, it's hidden by default */
        #nav ul {
            position:absolute;
            left:0;
            display:none;
            margin:0 0 0 -1px;
            padding:0;
            list-style:none;
        }
         
        #nav ul li {
            width:100px;
            float:left;
            border-top:1px solid #fff;
        }
         
        /* display block will make the link fill the whole area of LI */
        #nav ul a {
            display:block; 
            height:15px;
            padding: 8px 5px;
            color:#666;
        }
         
        #nav ul a:hover {
            text-decoration:underline; 
        }
 
/* fix ie6 small issue */
/* we should always avoid using hack like this */
/* should put it into separate file : ) */
*html #nav ul {
    margin:0 0 0 -2px;
}

JavaScript

$(document).ready(function () {
window.$j = jQuery.noConflict();     
    $j('#nav li').hover(
        function () {
            //show its submenu
            $j('ul', this).slideDown(100);
 
        },
        function () {
            //hide its submenu
            $j('ul', this).slideUp(100);        
        }
    );
     
});