JSFiddle - React, Tailwind, and code Playground

HTML

<div id="mainmenu">
	<ul class="menubar">
            <li class="first"><a href="#">1Menu 1Menu 4</a>
            	<ul class="submenubar">
                    <li class="subfirst"><a href="#">1Menu 1Menu 4</a></li>
                    <li class="subsecond"><a href="#">Menu 2Menu 1Menu 1Menu 4</a></li>
                    <li class="subthird"><a href="#">Menu 3Menu 1Menu 4</a></li>
                    <li class="subfourth"><a href="#">Menu 4Menu 4Menu 4Menu 4</a></li>
                </ul>
            </li>
            <li class="second"><a href="#">Menu 2Menu 1Menu 1Menu 4</a></li>
            <li class="third"><a href="#">Menu 3Menu 1Menu 4</a></li>
            <li class="fourth"><a href="#">Menu 4Menu 4Menu 4Menu 4</a></li>
	</ul>
</div>

CSS

#mainmenu{
    margin-bottom: 2.5em;
}
.menubar{
    position: fixed;
    top:0;
    left:0;
    max-height:10em;
    width:100%;
    list-style: none;
    background-color:#333333;
    text-align: left;
    margin:0;
    padding: 0;
    z-index: 1;
    border-bottom: 1px solid #ccc; 
}
.menubar .first {
    margin-left: 1em;
}
.menubar li{
    position: relative;
    display: inline-block;
    width:15em;
    text-align: center;
    font-family: 'Oswald', sans-serif;
    font-size: 1em;
    border-bottom: none;
    cursor: pointer;
    
    
}

.menubar li:hover{
        background-color:#6666ff;
}
.menubar a{
    display: block;
    padding: 0.5em 0.5em 0.5em 0.5em;
    text-decoration: none;
    color:#ffffff;
}



/* for submenus */

.menubar .first .submenubar {
    padding: 0;
    position: absolute;
    top:2em;
    left:0;
    width:auto;
    display: none;
    
    -webkit-box-shadow: 0px 13px 25px rgba(0,0,0, 0.2);
    -moz-box-shadow: 0px 13px 25px rgba(0,0,0, 0.2);
    box-shadow: 0px 13px 25px rgba(0,0,0, 0.2);
}

.menubar li .submenubar li {
    text-align: left;
    list-style-type: none;
    background-color:brown;
    display: block;
    color:#fff;  

}
.menubar > li > .submenubar > li:hover {
   background-color:black;
}
.menubar li:hover .submenubar{
    display: block;
}