Custom CSS does not work when a Theme is selected

Hello all,

I am currently using the "High Contrast Black" theme to set all the text in the Dashboard to be white. The issue is that when I modify the CSS for the CrossTab, nothing happens. Switching it back to the "Platinum" theme, it works as expected. My two follow up questions:

1. Is it possible to set the overall text to white instead of black when I am in the "Platinum" theme?

2. Is it possible to change the default CSS for standard components when using themes other than "Platinum"?

Thanks,

Hanks