JSFiddle - React, Tailwind, and code Playground

by learningforever

HTML

<h3>
  Hello, this border is too long
</h3>

<h4>
  Hello, this border should be small
</h4>

CSS

h3
{
  border-bottom: 3px solid #000;
}

h4::after
{
  content: '';
  border-bottom: 3px solid red;
  width: 10px;
}