JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
</head>

<body>
  <div id="header">
    HEADER
  </div>
  <div id="content">
    Test Content
  </div>
</body>
</html>

CSS

body{padding:0px;}

  * { 
    margin: 0;
    padding: 0;
  }
  body {
    background-color: orange;
  }
  div#header {
    background-color: red;
    height: 50px;
  }
  div#content {
    background-color: yellow;
    top:50px;
    bottom:0px;
    width:100%;
    position:absolute;
  }