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. I am currently on DS1.6. 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"?

CSS Code:

.sapzencrosstab-DataArea, .sapzencrosstab-RowHeaderArea, .sapzencrosstab-HeaderCellDefault,
.sapzencrosstab-ColumnHeaderArea, .sapzencrosstab-Crosstab, .sapzencrosstab-TableDivBackground,
.sapzencrosstab-DataCellAlternating, .sapzencrosstab-HeaderCellAlternating, .sapzencrosstab-DataCellDefault,
.sapzencrosstab-HeaderCellDefault {
    background: transparent !important;
}

Theme: High Contrast Black - does not work even when appending !important to the end of the code

Theme: Platinum - Works as expected but all the text in the dashboard becomes black

Thanks,

Hanks