JSFiddle - React, Tailwind, and code Playground

HTML

<div class="responsive-menu">
			<ul>
				<li tabindex="9999">Menu
					<ul>
						<li>Zomer</li>
						<li>Herfst</li>
						<li>Winter</li>
						<li>Lente</li>
					</ul>
				</li>
			</ul>
		</div>

CSS

li {
  list-style-type:none;  
}

.responsive-menu {
		display:block;
		background-color:black;
		color:white;
		text-align:center;
		padding:10px;
		font-size:200%;
	}
	
	.responsive-menu ul li ul li {
		padding:10px;
		border-bottom:solid 1px white;
		border-top:solid 1px white;
	}
	
	.responsive-menu ul li ul {
		display:none;
		font-size:60%;
		padding-top:30px;
	}
    .responsive-menu ul li:focus {
        outline: none;
    }
	.responsive-menu ul li:focus ul {
		display:block;
	}