JSFiddle - React, Tailwind, and code Playground

HTML

<div class="top_l">
    <li>Nav <span>▼</span>

        <ul> <a href="#">Title</a>
 <a href="#">Title</a>
 <a href="#">Title</a>

        </ul>
    </li>
</div>

CSS

.top_l {
    width: 340px;
    height: 60px;
    float: left;
}
.top_l li {
    height: 32px;
    padding: 8px 12px 0 12px;
    margin: 10px 0 0 6px;
    border: 1px solid transparent;
    -moz-border-radius: 4px;
    -webkit-border-radius: 4px;
    border-radius: 4px;
    float: left;
    -moz-transition: all .3s ease;
    -webkit-transition: all .3s ease;
    -ms-transition: all .3s ease;
    transition: all .3s ease;
    list-style: none;
    color: #A4A4A4;
    font: 20px Arial, Helvetica, sans-serif;
    font-weight: bold;
    font-variant: small-caps;
    text-shadow: 2px 2px 3px #000;
    position: relative;
    cursor: pointer;
}
.top_l li span {
    font: 14px Arial, Helvetica, sans-serif;
}
.top_l li:hover, .top_l li.active {
    color: #FFF;
    border: 1px solid #444;
}
.top_l li ul {
    width: 120px;
    height: 120px;
    background: #222;
    border: 1px solid #444;
    -moz-box-shadow: inset 0 0.1em 0.4em 0.1em #000;
    -webkit-box-shadow: inset 0 0.1em 0.4em 0.1em #000;
    box-shadow: inset 0 0.1em 0.4em 0.1em #000;
    display: none;
    position: absolute;
    top: 22px;
    left: 4px;
}
.top_l li ul a {
    width: 118px;
    height: 28px;
    padding: 10px 0 0 0;
    background: red;
    float: left;
    color: #FFF;
    font: 14px Arial, Helvetica, sans-serif;
    font-weight: bold;
    font-variant: small-caps;
    text-shadow: 1px 1px 1px #000, -2px -2px 2px #000;
}

JavaScript

$(document).ready(function () {
    $('.top_l li').click(function () {
        $('.top_l li').addClass('active');
        $('.top_l li ul').slideToggle();
    });
});