JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
  <div id="left"></div>
  <div id="right"></div>
</div>

CSS

html, body, #container { height: 100%; }
#left { width:200px; float:left; min-height: 100%; background-color:blue; }
#right { width:100%;  min-height: 100%; background-color:red; }