Hi FabrÃ*cio,
thank you for reminding me of this post. I have not been able to answer earlier, only now I have come back from the holidays.

Thanks for your suggestion, it works well. The last thing I'm fighting with is to get rid of the bright outline of the inner button groups (Preview/PDF, Documentation/Examples). I tried Frame(false), Shadow(false), ShadowMode(ShadowMode.None)... nothing works. The only thing that helped partially is StyleSpec("web-box-shadow: none; box-shadow: none"), but even this is not perfect and there still remains a light dark outline on the inner button group.

Is there a nice solution to this issue?

Thank you for your assistance.

Kind regards
Dan