JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="menu">
    <li><a href="">Home</a>

    </li>
    <li class="dropdown"><a href="#">ABCD</a>

        <ul>
            <li>	<a href="">About My Com</a>

                <li><a href="/Pages/news.aspx">News</a>

                </li>
                <li><a href="/Pages/file-s.aspx">Reso</a>

                </li>
                <li>	<a href="#">Self </a>

                    <ul>
                        <li>	<a href="#">Benefit </a>

                        </li>
                        <li>	<a href="#">Employer </a>

                        </li>
                        <li>	<a href="#">Member </a>

                        </li>
                    </ul>
                </li>
                <li><a href="/Pages/faqs.aspx">FAQs</a>

                </li>
                <li>	<a href="#">Contact Us</a>

                    <ul>
                        <li>	<a href="/Pages/contac.aspx">Contact</a>

                        </li>
                        <li>	<a href="/Pages/.aspx">Customer Service </a>

                        </li>
                        <li>	<a href="/Pages/te.aspx">Telephone </a>

                        </li>
                        <li>	<a href="/Pages/lmap.aspx"> Map</a>

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

CSS

#menu, #menu2, #container {
    width: 100%;
    margin: 0;
    padding: 1px 0 0 0;
    list-style: none;
    background: #111;
}
#menu li, #menu2 li {
    float: left;
    padding: 0 0 0 0;
    position: relative;
    line-height: 0;
}
#menu a, #menu2 a {
    float: left;
    height: 25px;
    padding-top: 0;
    /* "" */
    padding-bottom: 0;
    /* "" */
    padding-left: 10px;
    padding-right: 10px;
    color: #999;
    text-transform: uppercase;
    font: bold 12px/25px Arial, Helvetica;
    text-decoration: none;
}
#menu li:hover > a, #menu2 li:hover > a {
    color: #fafafa;
}
#menu li a:hover, #menu2 li a:hover
/* IE6 */
 {
    color: #fafafa;
}
#menu li:hover > ul, #menu2 li:hover > ul {
    opacity:1
}
/* Sub-menu */
 #menu ul, #menu2 ul {
    list-style: none;
    margin: 0;
    padding: 0;
    position: absolute;
    top: 40px;
    /* "": 50px */
    left: 0;
    z-index: 99999;
    background: #444;
    transition: opacity .5s ease-in-out;
    -webkit-transition: opacity .5s ease-in-out;
    -moz-transition: opacity .5s ease-in-out;
    -o-transition: opacity .5s ease-in-out;
    opacity:0;
}
#menu ul ul, #menu2 ul ul {
    top: 0px;
    left: 195px;
    /* "": 160px */
}
#menu ul li, #menu2 ul li {
    float: none;
    margin: 0;
    padding: 0;
    display: block;
    -moz-box-shadow: 0 1px 0 #111111, 0 2px 0 #777777;
    -webkit-box-shadow: 0 1px 0 #111111, 0 2px 0 #777777;
    box-shadow: 0 1px 0 #111111, 0 2px 0 #777777;
}
#menu ul li:last-child, #menu2 ul li:last-child {
    -moz-box-shadow: none;
    -webkit-box-shadow: none;
    box-shadow: none;
}
#menu ul a, #menu2 ul a {
    padding: 10px;
    height: 10px;
    width: 165px;
    /* "" */
    height: auto;
    line-height: 1;
    display: block;
    white-space: nowrap;
    float: none;
    text-transform: none;
}
#menu ul a, #menu2 ul a
/* IE6 */
 {
    height: 10px;
}
*:first-child+html #menu ul a, *:first-child+html #menu2 ul a
/* IE7 */
 {
    height: 10px;
}
#menu ul a:hover, #menu2...