GtkButtons currently have the following styling:
Normal - 1 level above main layer

Active - 1 level below main layer

So we press the button 2 layers/levels down
Do we really need that black top border?
Since the normal buttons are already "1 level above" the window layer, meaning 1 bit closer to the user if there would be a z-axis, wouldn't a press effect, that simply presses the button down TO THE layer of the rest enough?
Which would look like this:
Normal - 1 level above main layer

Active - on the main layer

Now we would press the button 1 layer/level down
@madsrh @clobrano ?
Post 18.10 discussion ofc :)

Current effect looks a bit too much in my opinion, for example near other borders:

I'll appreciate it to be left as is. it helps me when I get that extra feedback for pressed btn.
I'm in doubt here 🤔 It looks better for sure, but with the current design I really like the extra usability - it's just obvious. We could (as we do with everything else) test it and see how it feels 🤷♂️
I agree with Mads, I like the 3d effect for usability
How about lightening the top border a bit? When in clashes with the left and right borders it looks like there is a pixel missing
It looks not as sharp as it could look
I think it helps when there are disabled buttons around, but we can try to tweak it
I think it's perfect as is, it's very obvious and for some reason, really satisfying to look at for me.
To help with the sharpness, maybe a box-shadow on top might help refine the top corners? I can't test it right now but just an idea.

No luck. It looks about the same (slightly making the blur even more noticeable if you look closely) . The box-shadow attempt is on the right, and I had to do border-top-color: transparent or else the dark border on top would be 2px tall.
Edit: So I think we'll just have to live with it. :man_shrugging:
We could try to lower the darkness of the top border so the difference between the border and the top border is less leveling. Otherwise just close it. I think everyone beside me is liking it no use from my point of view to stress this any further =)
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I'm in doubt here 🤔 It looks better for sure, but with the current design I really like the extra usability - it's just obvious. We could (as we do with everything else) test it and see how it feels 🤷♂️