Popover transition enter doesn't work.

[krt-z]

I noticed this trying to port something form TailwindUI, but it shows up in the Popover example as well. It's easier to notice if you make the duration like duration-1000.

[lxsmnsyc]

It's because of the auto-focus, which is related to positioning and visibility too (fixed doesn't suffer from this problem). I'm not sure what the workaround here is though, but this should only affect elements that's undergoing CSS transitions.