SOURCE

let a=-1;
let b=50;
let c=100;
function setup(){
    createCanvas(500,500);
    background(255);
}
function draw(){
    background(255,10);
    a+=0.3;
    b+=0.3;
    c+=0.3;
    noFill();
    push();
    stroke(0);
    translate(250,250);
    rotate(a);
    translate(-100,-100);
    rect(0,0,250,250);
    pop();
    push();
    stroke(0,60);
    translate(250,250);
    rotate(b);
    rect(0,0,50,50);
    pop();
    push();
    stroke(0);
    translate(250,250);
    rotate(c);
    rect(0,0,30,30);
    pop();
}