JSFiddle - React, Tailwind, and code Playground

HTML

<nav></nav>
<div></div>

CSS

/** -- normalize -- */
* { margin: 0; padding: 0; border: 2 solid black; }
html, body { width: 100%; height: 100%; }

/** -- layout -- */
nav, div {
    height: 100%;
}

nav {
    float: left;
    width: 200px;
    
}

div {
    margin-left: 200px;
}

/** -- demo colors -- */
nav { background-color: #eee; }
div { background-color: #ddd; }