let xSpacing = 35;

let startW = 50; // width of first square

​

​

function setup() {

  createCanvas(600, 600);

  noLoop();

  noStroke();

}

​

function draw() {

  background("#08010A");

​

​

​

let i = 0; // index variable

  for (let y = 10; y < height; y += ySpacing) {

​

    for (let x = 0; x < width; x += xSpacing) {

  let r = random(100,150);

  let g = 100;

  let b = random(0,255);

    let a = random(0,255);

fill(r,g,b,a);

      square(x, y, startW-i*0.3); // x, y, w // square or a rectangle -- x and y are top left point

      i++; // the same as writing 'i=i+1' or 'i+=1'

    }

  }

}

​