I like to add to this.. had to use an other account.. but.. the problem is gone in the buttons – when I check the latest beta!
Might have been with Firefox, Chrome does not show this line inside the buttons.
I like the design… just getting used to it and maybe better for users with less sharp eyes to see the fields a bit better.
Thanks for making WP! Again.. the speed, at least in my tests is amazing fast on PHP 7.3
