JSFiddle - React, Tailwind, and code Playground

HTML

<div id='parent'>
  <div id='child'>

  </div>
</div>

CSS

#parent {
  position: relative;
  width: 500px;
  height: 300px;
  background-color: red;
}

#child {
  position: absolute;
  width: 70px;
  height: 70px;
  background-color: blue;
  left: 50%;
  top: 50%;
  border-radius: 50%;
  transform: translate(-50%, -50%);
}