JSFiddle - React, Tailwind, and code Playground

HTML

<canvas id="ctxt" width="500" height="500"></canvas>

JavaScript

var cvas = document.getElementById("ctxt");
var cx = cvas.getContext("2d");
cx.fillStyle = "rgba(0,0,0,1.0)";
cx.fillRect(200, 200, 300, 300);
setInterval(function() {
    cx.fillStyle = "rgba(255,255,255,0.01)"
    cx.fillRect(0, 0, 500, 500);
}, 20);