JSFiddle - React, Tailwind, and code Playground

HTML

<nav>
  <ul>
    <li><a href="#">Home</a></li>
    <li><a href="#">Photos</a></li>
    <li class="sub">
      <a href="#">Services (Drop Down)</a>
      <ul>
        <li><a href="#">Sub Link One</a></li>
        <li><a href="#">Sub Link Two Here</a></li>
        <li><a href="#">Sub Link Three</a></li>
        <li><a href="#">Sub Link Four Here</a></li>
      </ul>
    </li>
    <li><a href="#">About</a></li>
    <li><a href="#">Links</a></li>
    <li><a href="#">Contact</a></li>
  </ul>
</nav>

CSS

nav {
    text-align:left;
}

nav ul {
    margin:0;
    padding:0;
    z-index:100;
}

nav ul ul {
    background:#fff;
    list-style:none;
    position:absolute;
    margin: 0;
    text-align:left;
    left: -999px;
}

nav ul ul:before{
    content:"";
    position: absolute;
    z-index: 0;
    left: -4px; right: -4px;
    top: 2px;
    bottom: -6px;
    border-radius: 0px;
    background: -moz-linear-gradient(top,  rgba(0,0,0,0) 0%, rgba(0,0,0,0.65) 100%);
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(0,0,0,0)), color-stop(100%,rgba(0,0,0,0.65)));
background: -webkit-linear-gradient(top,  rgba(0,0,0,0) 0%,rgba(0,0,0,0.11) 100%);
background: -o-linear-gradient(top,  rgba(0,0,0,0) 0%,rgba(0,0,0,0.65) 100%);
background: -ms-linear-gradient(top,  rgba(0,0,0,0) 0%,rgba(0,0,0,0.65) 100%);
background: linear-gradient(top,  rgba(0,0,0,0) 0%,rgba(0,0,0,0.65) 100%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#00000000', endColorstr='#a6000000',GradientType=0 );
    box-shadow: inset 0 0 3px 2px rgba(255,255,255,0.9);
}

nav ul ul li {
    position: relative;
    z-index: 1;
    float:none;
    display: list-item;
    margin:0;
    padding:5px 5px;
    font-size:.85em;
    background-color: white;
}

nav ul ul a {
    padding:5px 0;
    margin-bottom:1px;
    white-space:nowrap;
}

nav li {
    -moz-box-orient:vertical;
    vertical-align:auto;
    position:relative;
    display:inline;
}

nav li:hover ul {
    left:0;
}