JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="mainMenu horizontalMenu bulletless fullWidth bold">
    <li class="showSubMenu">
        <div>Resumes &amp; Cover Letters &#x25BE; </div>
        <ul class="mainSubMenu bulletless">
            <li><a>Resumes</a></li>
            <li><a>Cover Letters</a></li>
            <li><a>Interviews</a></li>
        </ul>
    </li><li class="active"><div>Industries &amp; Professions</div>
    </li><li><a>Jobs &amp; Internships</a></li>
 </ul>

CSS

.horizontalMenu li{    
    display: inline-block;
}
.mainMenu > li{
    border: 1px solid black;
    position:relative;
}
.mainMenu a, .mainMenu div{
    display: block;
    padding: 10px 20px;
    
}
.mainSubMenu{
    position: absolute;
    width:100%;
}

.mainSubMenu li{
    display: block;
    border: 1px solid grey;            
}