JSFiddle - React, Tailwind, and code Playground

HTML

<aside></aside><main></main> 

<script>
  var w = window.innerWidth/100;
  var e = document.getElementsByTagName("aside")[0].style;
  e.display = "inline-block";
  e.backgroundColor = "lightblue";
  e.width = 14*w + "px";
  e.height = "100px";
  e.marginRight = 0.5*w + "px";

  e = document.getElementsByTagName("main")[0].style;
  e.display = "inline-block";
  e.backgroundColor = "green";
  e.width = 85.5*w + "px";
  e.height = "100px";   

  e = document.getElementsByTagName("body")[0].style;
  e.margin = e.padding = "0";
  e.backgroundColor = "black";
  
</script>

CSS

aside, main{
  display:inline-block;
}

body{
  overflow:hidden;
}