Comment by squiffy

This is great, thanks. A small fix I made to stop console warnings was to change:

  x.fillStyle = '#' + ((r >> 8) & 0xffffff).toString(16).padStart(0, 6);

to:

  x.fillStyle = '#' + ((r >> 8) & 0xffffff).toString(16).padStart(6, '0');

as the pad target length is the first parameter of padStart.