JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
<div class="m">
<div class="test">

</div>
</div>
</div>

CSS

.parent {
  position: relative;
  width: 300px;
  border: 1px solid black;
}
.m {
  padding: 40px;
}
.test {
  background: #999;
  height: 100px;
}
.test::after {
  content: "after";
  background: red;
  position: absolute;
  top: 5px;
  left: 5px;
}