JSFiddle - React, Tailwind, and code Playground

HTML

<p><img src="http://i.stack.imgur.com/I2BNn.png" /></p>

<ul id="nav">
    <li><span></span><a href="#">Home</a></li>
    <li><span></span><a href="#">Products</a></li>
    <li><span></span><a href="#">Really Long Nav Item</a></li>
</ul>

CSS

body {font-family:Helvetica,Arial,sans-serif;font-size:12px;}

#nav {background-color:#000;overflow:hidden;}
#nav li {float:left;position:relative;}
#nav a {display:block;background:transparent;color:#fff;font-weight:bold;text-decoration:none;padding:20px;position:relative;}

#nav li:hover span {
    position:absolute;
    left:50%;top:50%;
    margin-left:-35%;
    width:70%;height:0px;
    box-shadow:0 0 20px 12px rgba(150, 180, 200, .6);
    border-radius:10px 6px;
}