JSFiddle - React, Tailwind, and code Playground

HTML

<header>Header</header>
<aside>Aside</aside>
<div id="map"></div>

CSS

header { background: #F1F1F1; }
aside, #map {background: #fff }

aside, #map { position: absolute; top: 100px; bottom: 0; } 
header { height: 100px; box-shadow: 0 4px 4px #ccc; }
aside {  left: 0;  width: 100px; box-shadow: 5px 0 4px -2px #ccc; }
#map { z-index: -1; right: 0; left: 100px; }