<html>
<head>
<style>
body {padding:0px;margin:0px;}
</style>
</head>
<body>
<canvas id="demo"></canvas>
<script>
var c=document.getElementById('demo');
var cc=c.getContext("2d");

//array of gray colors - these are very similar colors, let's hope this works out well.
var items = ["#96ceb4","#ffeead","#ff6f69","#ffcc5c","#88d8b0"];

window.addEventListener("load",setDimensions);
window.addEventListener("resize",setDimensions);

setInterval(draw,50);

function setDimensions() {
	c.width=window.innerWidth;
	c.height=window.innerHeight;
};

function draw() {

	for (x=0; x < 10; x++) { //10 blocks at a time
		
		cc.fillStyle=items[Math.floor(Math.random()*items.length)]; // random color from array "items"
		
		cc.globalAlpha=0.5; // blocks will be semi-transparent
		
		var size=Math.floor((Math.random()) * 60) + 1; //random square-size between 1 and 60px	
		
		cc.fillRect(Math.floor(Math.random()*c.width - 30), Math.floor(Math.random()*c.height -30), size , size); //random location & random size!	
		
	};
};

</script>
</body>
</html>