As Jaime said, the recommended solution for all this is to use custom drawn controls, i.e. controls which don't depend on the default drawing being done by the system.
I don't use them normally so I can't recommend any one set, but there are quite a lot of them. Search the wiki for a few and use whchever takes your fancy.
Beyond that, what I do the few times I need to tweak how some control draws is to add a handler to its OnPaint event. Unfortunately (for your use case) both TPageControl and TTabSheet descends almost directly from TWinControl and the OnPaint event is introduced by TCustomControl, which means they don't have it.
I'm not sure what else I can tell you, except ... just let it draw as it wants! That's what desktop theming is for
BTW, completely unrelated but "Google translate" did you a diservice: shellfish? Henk? Ka bug? WTH?