After I changed the "--bus" CSS variable from 30px to 40px, I got the stepping effect.
I always loved making web remakes of common GIF illusions  where you can mess with variables and see what impact it has. This is a perfect example of that.
The black and white lines in the background are only 1px wide and after moving one pixel, the busses touch a black bar either at the left or the right.
My brain feels broken.
If I unfocus my eyes and look at only one of the buses, I can see that it is moving at a constant rate across the stripes. But the moment I try to look at both, the illusion takes over. I can sort of get half the illusion by focusing my attention on one of the buses, but still 'noticing' the movement of the other: in that case I will see the bus I am paying attention to move at a constant rate and the other bus move in a stepping motion.
Does it imply that if I drive a brighter color car, it will appear that I am driving faster? (when compared to a darker color car traveling at the same speed)
But I’ve read that if you look at a darker car moving at you, you’ll perceive it is a little less threat than e.g. red or neon-colored one, because dark contours “grow” slower. (Similar thing, but can also be a stereotype bs, learned lots of these before debunking via internet era came)
McCollough originally reported that these aftereffects may last for an hour or more. However, Jones and Holding (1975) found that 15 minutes of induction, when time-elapse testing is employed, can lead to an effect lasting up to 2.8 months.
Also shows what it looks like in pure black & white at the end.
Do these separate illusions share a common cause (high/low contrast colors juxtaposed)?