PythSine

float x, y;
float sz, msz, big_sz;
float theta;
color bg = #334D5C;
color sqcol = #EFC94C;
color sqstr = #DF5A49;

void setup() {
  size(500, 500);
  background(255);
  stroke(0);
  sz = 100;
  big_sz = 1.4*sz;
  x = width/2;
  y = height/2;
  rectMode(CENTER);
}

void draw() {
  background(bg);
  translate(x, y);
  msz = map(sin(theta), -1, 1, sz, sz*2);

  fill(sqcol);
  strokeWeight(25);
  stroke(sqstr);

  rect(0, 0, msz, msz, 20);

  for (int i=0; i<4; i++)
  {
    pushMatrix();
    rotate(i*radians(90));
    rect(msz/2+big_sz/2, -msz/2+big_sz/2, big_sz-msz/2+sz/2, big_sz-msz/2+sz/2, 25);
    popMatrix();
  }

  theta += 0.0523;
}