JSFiddle - React, Tailwind, and code Playground

HTML

<div class="header">
   <h1>title</h1>
 </div>
 <div class="menu"></div>

CSS

.header {
   width: auto;
   height: 100px;
   background-color: gray;
   text-align: center;
   line-height: 50px;
   /* border: 1px solid black; */
   overflow: auto;
 }

 .menu {
   background-color: green;
   height: 80px;
   /* border: 1px solid black; */
 }