JSFiddle - React, Tailwind, and code Playground

HTML

<div>

</div>

CSS

div {
  position: relative;
  width:300px;
  height: 200px;
  background: black;
}
div::after {
  content: "";
  position: absolute;
  top: 20px;
  left: 20px;
  background: linear-gradient(90.04deg, orange 11.28%, yellow 87.74%);
  z-index: -1;
  width:300px;
  height: 200px;
}