JSFiddle - React, Tailwind, and code Playground

by lonking

HTML

<div id="top"></div>
  <div id="rest"></div>

CSS

#top {
 position: fixed;
 left: 0px;
 top: 0px;
 width: 100%;
 height: 40px;
 background-color: white;
}

#rest {
 position: fixed;
 top: 40px;
 left: 0px;
 width: 100%;
 height: calc(100% - 40px);
 background-color: lightgrey;
}