JSFiddle - React, Tailwind, and code Playground

HTML

<hr/>

CSS

hr {border: 0; height: 5px; background: #333; background-image: -webkit-linear-gradient(left, #ccc, #333, #ccc); background-image: -moz-linear-gradient(left, #ccc, #333, #ccc); background-image: -ms-linear-gradient(left, #ccc, #333, #ccc); background-image: -o-linear-gradient(left, #ccc, #333, #ccc);}