Thank you, that already helped a lot! I am still looking for the following:

Selected tab title is white, with a green (#00ae9d) underline.
Hover over a tab title (currently not active/selected) leads to white tab title without underline.
Not selected tab titles are grey, without an underline.

Also regular text (e.g. on second tab) is now black/grey on black background. That should be also white text.