JSFiddle - React, Tailwind, and code Playground

HTML

<div id="navBar">
    <ul style="float: left; padding-left: 5px;">
        <li>
            <a href="#">A</a>
        </li>
        <li>
            <a href="#">B</a>
        </li>
        <li>
            <a href="#">C</a>
            <ul>
                <li><a href="#">This is a thing.</a></li>
                <li><a href="#">Cool man</a></li>
                <li><a href="#">Linus</a></li>
            </ul>
        </li>
        <li>
            <a href="#">D</a>
            <ul>
                <li><a href="#">Gerg.</a></li>
                <li><a href="#">Weeeeeeeeeeeeeeeeeeeeee</a></li>
                <li><a href="#">asdf idiot</a></li>
                <li><a href="#">blah</a></li>
            </ul>
        </li>
    </ul>
</div>

CSS

#navBar
{
    background-color: rgb(70,70,70);
    height: 32px;
    color: white;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 100;
}

#navBar *
{
    vertical-align: middle;
    margin: 0px;
}

#navBar > ul
{
    list-style: none;
    text-decoration: none;
}

#navBar > ul > li
{
    float: left;
    position: relative;
}

#navBar > ul > li > a
{
    display: block;
    padding: 7px;
    color: White;
}

#navBar > ul > li:hover > a
{
    background-color: #999;
}

#navBar > ul > li > ul
{
    left: 0;
    top: 32px;
    display: none;
    position: absolute;
    max-height: 300px;
    border: 1px solid #999;
    background-color: #eee;
    padding: 5px 0px 10px 0px;
    white-space: nowrap;
}

#navBar > ul > li:hover > ul
{
    display: block;
}

#navBar > ul > li > ul > li > a
{
    padding: 10px;
    display: block;
    color: black;
}
#navBar > ul > li:hover > ul > li:hover
{
    background-color: #999;
}
#navBar > ul > li:hover > ul > li:hover > a
{
    color: white;
}