JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer">
  <div class="inner"></div>
</div>

CSS

body {
  background-color: gray;
}
.outer {
  width: 200px;
  height: 200px;
  background-color: blue;
  position: relative;
}
.inner {
  height: 20px;
  width: 20px;
  border-radius: 10px;
  position: absolute;
  left: 90px;
  top: 90px;
  background-color: yellow;
}