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3D illusion
(i.imgur.com)
While this is just a static 2d image, it looks like blue is above the screen (for me, for some others it's below, or red is above).
Thanks to comments, here some explanations https://en.wikipedia.org/wiki/Chromostereopsis
Edited: added Wikipedia link
I've noticed this effect on business signs so I don't think that's the cause. Blue specifically seems affected, and you can notice a parallax difference too even when they're the same distance. I assumed it had to do with my glasses bending the light differently or something.
I've definitely seen it when the colours are in focus/sharpness the same, e.g. with red words on my phone screen standing out in front of the rest.
https://en.wikipedia.org/wiki/Chromostereopsis
Found courtesy of another comment
Edit: oh and now I see OP also already got the link