Matching new Libadwaita theme

[sith-on-mars]

The Libadwaita theme was updated in Gnome 43. For me the biggest visual difference compare to Libadwaita in Gnome 42 is tab:

Here is a screenshot of tabs in Gnome 42:

Current KvLibadwaita looks more closer to Libadwaita in Gnome 43 than in 42. Of course, there's still room for improvement.