Press spacebar to pause. These horizontal lines are perfectly straight even though they sometimes look angled. Pause the animation with Space at the right time to fully see the illusion. https://en.wikipedia.org/wiki/Caf%C3%A9_wall_illusion Feel free to use my scripts if you want. Oh, and 100% pen. v1.1 update - Added @griffpatch's square filling script to improve performance. Thanks griffpatch!
