JSFiddle - React, Tailwind, and code Playground

by seefeld

HTML

<div class="box_header">Testing</div>

CSS

.box_header:after {
    background: none repeat scroll 0 0 #42B3E5;
    bottom: 0;
    content: "";
    display: block;
    height: 2px;
    margin-top: 10px;
    width: 50px;
}