html, body {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  background: #292a33;
  overflow: hidden;
}
let r, angle;

function setup() {
  createCanvas(windowWidth, windowHeight);

  r = 100;
  angle = 0;
}

function draw() {
  clear();
  translate(width / 2, height / 2);

  push();
  noFill();
  stroke(240);
  circle(0, 0, r * 2);
  pop();

  const x = cos(angle) * r;
  const y = sin(angle) * r;
  circle(x, y, 10);

  angle += 0.01;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdn.jsdelivr.net/npm/[email protected]/lib/p5.min.js