JSFiddle - React, Tailwind, and code Playground

HTML

<span id="header-bars">headerbars</span>
<nav class="header-nav">Navigation</nav>

CSS

.header-nav {
  display: none;
}

.header-nav.show {
  display: block;
}

JavaScript

var headerBars = document.getElementById('header-bars');

headerBars.addEventListener('click', function() {
	  document.querySelector('.header-nav').classList.toggle('show');
});