createCanvas(windowWidth, windowHeight);

  background(31);

  noStroke();

  for (let i = 0; i < 1000; i++) {

    let x = random(width / 2);

    let y = random(height);

    let diameter = map(y, 0, height, 30, 10);

    fill(random(31), random(190), random(190, 255), 190);

    circle(x, y, diameter);

  }

  for (let i = 0; i < 1000; i++) {

    let x = random(width / 2, width);

    let y = random(height);

    let diameter = map(y, 0, height, 10, 30);

    fill(random(190, 255), random(127), random(31), 190);

    rect(x, y, diameter);

  }

}

​