How to change text color of short description lines

In gridscreen, I'm trying to change the color of the text that is under the poster. I believe they are short desc. 1 and 2.

 Title: "Preferences"
            ContentType: "Preferences"
            ShortDescriptionLine1: "Preferences"
            ShortDescriptionLine2: "Version " + getGlobalVar("channelVersion", "Unknown")
            HDPosterUrl: viewController.getThemeImageUrl("hd-preferences.jpg")
            SDPosterUrl: viewController.getThemeImageUrl("hd-preferences.jpg")
        })

Thank you.