JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer">
  outer Stuff
  <div id="inner">
    Innner stuff
  </div>
</div>

CSS

#inner{
  width: 50%;
  background: blue;
  border: 1px solid black;
  margin: 0 auto;
  height: auto;
  position: relative;
}

#outer{
  width: 90%;
  background: red;
  height: 200px;
}