switch classic theme tab colouring

classic theme currently uses dark grey background for active tab and light grey background for inactive tab. unfortunately, the inactive tab bg colour matches tab bg colour, so visually the inactive ones seem more related to the tab itself.
darker also is usually associated with 'greyed out' or inactive.

tab colours for active/inactive in the classic theme should be switched.

additionally, same logic should be applied for option buttons (like ip/dns selection in host properties)