JSFiddle - React, Tailwind, and code Playground

HTML

<div id='menu'>
	<ul id='nav'>
		<li>
			<a href='#'>Level 1</a>
			<ul>
				<li><a href='#'>Level 1-1</a>
					<ul>
						<li><a href='#'>Level 1-1-1</a></li>
						<li><a href='#'>Level 1-1-2</a></li>
					</ul>	
				</li>
				<li><a href='#'>Level 1-2</a>
					<ul>
						<li><a href='#'>Level 1-2-1</a></li>
						<li><a href='#'>Level 1-2-2</a></li>
					</ul>	
				</li>
                <li><a href='#'>Level 1-3</a>
					<ul>
						<li><a href='#'>Level 1-3-1</a></li>
						<li><a href='#'>Level 1-3-2</a></li>
					</ul>	
				</li>
			</ul>
		</li>
	</ul>
</div>
<div class='form'>
    <form>
		<select>
			<option selected='true'> 1 </option>
			<option> 2 </option>
			<option> 3 </option>
		</select>
        <input type='button' value="Go"/>
    </form>
</div>

CSS

#menu {
    position: relative;
    z-index: 1;
    clear: both;
}
	
#nav{
    height: 39px;
    font: 14px Arial,Verdana,sans-serif;
    background: #f8f8f8;
    border: 1px solid #DDDDDD;  
    border-radius: 3px;
    min-width:500px;
    margin-left: 0px;
    padding-left: 0px;
}   

#nav li{
    list-style: none;
    display: block;
    float: left;
    height: 40px;
    position: relative;
    border-right: 1px solid #DDDDDD;
}

#nav li a{
    padding: 0px 30px 0px 30px;
    margin: 0px 0;
    line-height: 40px;
    text-decoration: none;
    border-right: 1px solid #DDDDDD;
    height: 40px;
    color: #6791AD;
    font-weight: bold;
}

#nav ul{
    background: #f2f5f6; 
    padding: 0px;
    border-bottom: 1px solid #DDDDDD;
    border-right: 1px solid #DDDDDD;
    border-left:1px solid #DDDDDD;
    border-radius: 0px 0px 3px 3px;
    box-shadow: 2px 2px 3px #ECECEC;
    -webkit-box-shadow: 2px 2px 3px #ECECEC;
    -moz-box-shadow:2px 2px 3px #ECECEC;
    width:200px;
}

#nav li:hover{
    background: white;
}
#nav li a{
    display: block;
}
#nav ul li {
    border-right:none;
    border-bottom:1px solid #DDDDDD;
    width:200px;
    height:39px;
}

#nav ul li li {
 	background: #f2f5f6; 
    padding: 0px;
    border-bottom: 1px solid #DDDDDD;
    border-right: 1px solid #DDDDDD;
    border-left:1px solid #DDDDDD;
    border-radius: 0px 0px 3px 3px;
    box-shadow: 2px 2px 3px #ECECEC;
    -webkit-box-shadow: 2px 2px 3px #ECECEC;
    -moz-box-shadow:2px 2px 3px #ECECEC;
    width:200px;
}

#nav ul li ul {
 	background: #f2f5f6; 
    padding: 0px;
    border-bottom: 1px solid #DDDDDD;
    border-right: 1px solid #DDDDDD;
    border-left:1px solid #DDDDDD;
    border-radius: 0px 0px 3px 3px;
    box-shadow: 2px 2px 3px #ECECEC;
    -webkit-box-shadow: 2px 2px 3px #ECECEC;
    -moz-box-shadow:2px 2px 3px #ECECEC;
    width:200px;
}

#nav ul li a {
    border-right: none;
    color:#6791AD;
    text-shadow: 1px 1px 1px #FFF;
    border-bottom:1px solid...