Steps to reproduce: 1. go to https://www.lematelasvert.fr 2. bring your mouse over the "matelas" or "accessoires" buttons 3. notice how it animates with a drop shadow which looks fine during the animation 4. notice how when the animation ends the shadow is now clipped This looks fine in both Firefox and Chrome.
Created attachment 465820 [details] Screenshot
Created attachment 465821 [details] Screen recording
Probably a dup of bug 207586.
<rdar://problem/108101967>