7a25c98 increased the height of the tabbar.

However it seems the height of the darkened area for inactive tabs (when "darken inactive tabs" is set in preferences) was not adjusted accordingly.

Therefore inactive tabs have a light strip at the bottom:

My personal preference would be to revert 7a25c98 altogether since I don't see any advantage in the increased height (see also comment on the commit) which would inherently fix this issue, too (as well as #1010).