The perpendicular lines that do not match row to row create an illusion of the lines between them being not parallel.
Submitted as an answer to the Showcase of Optical Illusions question on TeX SX.
Click the Illusions tag below to see more!
Our searchable collection of LaTeX examples is a great place to look when you're using a LaTeX package for the first time (or the first time in a while!).
Show off your awesome LaTeX skills by contributing examples to the gallery. You can publish any Overleaf project with a couple of clicks.
New examples of LaTeX packages and techniques are added all the time. Follow us on twitter for the highlights!