WTF! That mindfuck isn't possible!!?!? I know the shadow is casting there, so the grey ones are even darker, but that doesn't look remotely close to A :X
Nope, they are - christ, that's one of the most evil optical illusions I've ever seen, I didn't believe it either, but if you stare directly and intently at B and just take notice of A in your peripheral vision, you'll see they're the same!