float r,g,b;
color outer, inner, mid_outer, mid_inner;

void setup( ) {
  size(600,600);
  background(51);
  noStroke();
  r = random(0,255);
  g = random(0,255);
  b = random(0,255);
  outer = color(r,g,b);
  r = random(0,255);
  g = random(0,255);
  b = random(0,255);
  inner = color(r,g,b);
}

void draw( ) {
  mid_outer = lerpColor(outer, inner, .33);
  mid_inner = lerpColor(outer, inner, .66);
  fill(outer);
  rect(60, 60, 480, 480);
  fill(mid_outer);
  rect(100, 100, 400, 400);
  fill(mid_inner);
  rect(165, 200, 270, 260);  
  fill(inner);
  rect(210, 260, 180, 160);
}
  
void mousePressed() {
  r = random(0,255);
  g = random(0,255);
  b = random(0,255);
  outer = color(r,g,b);
  r = random(0,255);
  g = random(0,255);
  b = random(0,255);
  inner = color(r,g,b);
}