Can't change color of calendar view selection


I just found a problem with themes. I can not change the color of the view selector for calendar and agenda. By this I mean the menu on top that has “Day”, “Work Week”, “Week” and so on. It’s always blue for custom themes. The selected and hovered over buttons have blue text and the blue underline to be exact.
I looked through the code and couldn’t find anything that worked. It DOES change color when I choose a pre-made theme though. So I copied parts of the code of that theme to my custom theme to see where the color is defined. But nothing worked. So I just saved the pre-made theme and imported it as a custom one. And now this very same theme has blue text in the mentioned area when taken from the custom themes list but the theme’s altered color when taken from the original list.

Does anybody have an idea what the reason could be? Is there a solution?

Thank you!