JSFiddle - React, Tailwind, and code Playground

HTML

<div>Test</div>

CSS

div {
  width: 200px;
  height: 200px;
  display: block;
  position: relative;
}

div::after {
  content: "";
  background: url(http://s.hswstatic.com/gif/evil-robots-3b.jpg);
  opacity: 0.5;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  position: absolute;
  z-index: -1;   
}