JSFiddle - React, Tailwind, and code Playground

HTML

<div id="a">
  <div id="b">
  </div>
</div>

CSS

html, body {
    height: 100%;
    background: red;
    margin: 0;
  }
  #a {
    min-height: 100%;
    background: green;
  }
  #b {
    min-height: 100%;
    background: yellow;
  }