That doesn't answer my question. I know GTK3 uses CSS for styling now. What I'm asking about is the translucency effects, how they are achieved in the CSS. Do you just include an alpha channel in your colors and it just works, or what?
Looks amazing! But if I could make a suggestion, the active tab looks like it drops down from the title/toolbar, but it doesn't blend with it. I think it would look better if the tab blended with the view area, or if all the corners were rounded.