SOURCE

let a=0;
function setup(){
    createCanvas(500,500);
    background(255);
}
function draw(){
    background(255,10);
    a+=3;
    noFill();
    push();
    stroke(10);
    translate(250,250);
    rotate(a);
    translate(-100,-100);
    rect(30,20,250,250);
    pop(1);
    push(1);
    stroke(60);
    rotate(a)
    translate(10,100);
    rect(170,170,80,60);
    pop(a);
}