(I open a new ticket. The original question was here:
but that topic is already answered and my question probably won't be seen anymore.)
The CodePen shows some variation of a jalousie effect, that Shaun posted as an example in the forum post mentioned above. Playing around with that (mostly adapting it to vw and vh), it happened at one point that there was a "running shadow" introduced. It happens very subtle after the second animation is coming to its end: the slices are fading out, and just a tiny little bit later the slice flashes up for a moment again in a very, very bight grey. Hope you can see that.
I was wondering, why this "running shadow" effect is happening?
Thanks for any hints!