The blue horizontal stripes above are oblique – are they?
Slider(near the bottom, below “degrees”) you can compensate the obliqueness until satisfied. For me 2–3° seems fine.
Check marks” or “
Odd reverse”. Are the blue horizontal stripes still parallel?
The compensation does not work fully, the stripes assume something of an horizontal S-shape. Also it depends on your gaze direction.
This effect became popular in July 2017, originally designed by Victoria Skye, which I simplified a little. A closer approximation to her version is here, the present one allows to compensate the seeming angle and thus measure it.
I still haven’t the foggiest how this works. It is certainly not the Café Wall illusion, even if initially thus misnomed.