JSFiddle - React, Tailwind, and code Playground

HTML

<h2>
Contact Details</h2>
<button type="button" class="edit_button" >My Button</button>

CSS

h2 {
	border-bottom-width: 1px;
	border-bottom-style: solid;
	border-bottom-color: gray;
	float: left;
	margin: 0;
	padding: 0;
}
.edit_button {
	float: right;
}