Is it possible to customize ZC Themes?

Is it possible to customize ZC Themes?

I understand you can choose a layout and customize Brand Color, App Header, Menu, and Sub-Menu components, but can you override some of the default theme settings with CSS or a config file? For example, 
- Table highlight color
- Listview auto filter highlight and text colors
- Main nav 'selected' color

I probably know the answer, but was wondering if there's a hack that could be applied.