JSFiddle - React, Tailwind, and code Playground

HTML

<button name="button" onclick="aparece()">Click Me</button>

<section id="box">
	<p>Eu sou o Maior!</p>
</section>

CSS

button {
	position: fixed;
	right: 0;
	bottom: 0;	
	width: 5px;
}

#box {
	display: none;	
}

button:hover {
	width: 100px;
}

JavaScript

function aparece() {
	document.getElementById('box').style.display = "block";
}