JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<body>
  <canvas id="canv1" />
</body>    
</html>

CSS

canvas {
    position: absolute; 
    left: 0px; 
    right: 0px; 
    bottom: 0px; 
    top: 0px
}

JavaScript

var ctx = document.getElementById('canv1').getContext('2d');        
ctx.fillRect(289, 139, 500, 500);