JSFiddle - React, Tailwind, and code Playground

HTML

<a href="#">
  <img src="//dummyimage.com/50">
</a>

CSS

a {
  display: block;
  text-align: center;
  position: relative;
}
a:after {
  content: "";
  width: 100%;
  position: absolute;
  left: 0;
  top: 50%;
  height: 1px;
  background: green;
  z-index: -1;
}