JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header" style="top:80px;position:fixed;z-index:9999;">
    <ul id="nav">
        <li><a href="#">Laptops</a>

            <ul>
                <li><a href="#">Laptops</a>
                </li>
                <li><a href="#">Macbooks</a>
                </li>
                <li><a href="#">Chromebooks</a>
                </li>
                <li><a href="#">Laptop Chargers</a>
                </li>
                <li><a href="#">Laptop Sale</a>
                </li>
            </ul>
        </li>
        <li><a href="#">Desktops</a>

            <ul>
                <li><a href="#">Desktop PCs</a>
                </li>
                <li><a href="#">Mac PCs</a>
                </li>
                <li><a href="#">All-In-One PCs</a>
                </li>
                <li><a href="#">Monitors</a>
                </li>
                <li><a href="#">Desktop Offers</a>
                </li>
            </ul>
        </li>
        <li><a href="#">Network & Storage</a>

            <ul>
                <li><a href="#">Modems & Routers</a>
                </li>
                <li><a href="#">External Hard Drives</a>
                </li>
                <li><a href="#">Internal Hard Drives</a>
                </li>
                <li><a href="#">USB Flash Drives</a>
                </li>
                <li><a href="#">Portable Media</a>
                </li>
            </ul>
        </li>
    </ul>
</div>
<div>CONTENT..... MORE CONTENT..... EVEN MORE CONTENT..... LOTS oF...

CSS

#nav, #nav ul {
    list-style: none outside none;
    margin: 0;
    padding: 0;
    z-index:9998;
    position:relative;
}
#nav {
    font-family:"Lucida Sans Unicode", Verdana, Arial, sans-serif;
    font-size: 13px;
    height: 36px;
    list-style: none outside none;
    margin: 40px auto;
    text-shadow: 0 -1px 3px #202020;
    width: 960px;
    /* border radius */
    -moz-border-radius: 4px;
    -webkit-border-radius: 4px;
    border-radius: 4px;
    /* box shadow */
    -moz-box-shadow: 0px 3px 3px #cecece;
    -webkit-box-shadow: 0px 3px 3px #cecece;
    box-shadow: 0 3px 4px #8b8b8b;
    /* gradient */
    background-image: -webkit-gradient(linear, left bottom, left top, color-stop(0, #787878), color-stop(0.5, #5E5E5E), color-stop(0.51, #707070), color-stop(1, #838383));
    background-image: -moz-linear-gradient(center bottom, #787878 0%, #5E5E5E 50%, #707070 51%, #838383 100%);
    background-color: #5f5f5f;
    
       background-color: #5F5F5F;
    background-image: -moz-linear-gradient(center bottom , #787878 0%, #5E5E5E 50%, #707070 51%, #838383 100%);
    border-radius: 4px 4px 4px 4px;
    box-shadow: 0 3px 4px #8B8B8B;
    font-family: "Lucida Sans Unicode",Verdana,Arial,sans-serif;
    font-size: 13px;
    height: 36px;
    list-style: none outside none;
    margin: 40px auto;
    position: fixed;
    text-shadow: 0 -1px 3px #202020;
    top: -40px;
    width: 960px;
}
#nav li {
    border-bottom: 1px solid #575757;
    border-left: 1px solid #929292;
    border-right: 1px solid #5d5d5d;
    border-top: 1px solid #797979;
    display: block;
    float: left;
    height: 34px;
    position: relative;
    width: 150px;
}
#nav > li:first-child {
    border-left: 0 none;
    margin-left: 5px;
}
#nav ul {
    left: -9999px;
    position: absolute;
    top: -9999px;
    z-index: 2;
}
#nav ul li {
    background: none repeat scroll 0 0 #838383;
    box-shadow: 5px 5px 5px rgba(0, 0, 0, 0.5);
    width: 100%;
    height:auto;
}
#nav li a {
   ...