The theme is using its "Private browser" theme for the regular window. Its not the bright colours but the darker one. Annoying as I can't quickly differentiate between the two windows. I have tried refreshing the browser already and no difference.

Installing this addon creates a copy called "Firefox Radiance" which looks the same with a slight difference in the tab colour.

Finally I can see the active tab.
It actually installs two versions, very similar to each other.
One is "firefox alpenglow", and the other is "firefox radiance" which is my favorite.