JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="tab">First Box</div><div class="tab">Second Box</div> 
</div>

CSS

.container {
max-width: 500px;
    overflow: auto;
height: 300px;
    background-color: orange;
}

.tab {
    display: inline-block;
    width: 50%;
    backround-color: orange;
    	text-align: center;
	width: 50%;
	box-shadow: 0px 0px 0px 2px red inset;
	display: inline-block;
	padding: 0 0px;
	letter-spacing: 1px;
}