Change the font color of an active page within the top navigation

Can you tell me how to change the font color of an active page within the top navigation of the Catch Box theme? We are using the Light color scheme of Catch Box but would like the font color to be red after the user selects the page. Currently it becomes bold and white when the page is active, we would like it to be bold and red. http://www.ndatl.k12.nd.us/