JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
  <span>child</span>
</div>

CSS

#container {
  background: blue;
  position: relative;
}

span {
  background: red;
  color: white;
  display: inline-block;
  left: 50%;
  padding: 8px;
  position: relative;
  transform: translateX(-50%);
}