In the last "Theme" Box, Theme Global Items, Under Applications, Background. That will change all the backbrounds that have text in front of it, SMS, Messages, Options.
For SMS, in SMS options, Conversation Style need to be set to Stripes.Hope this helps.
Won't that only make the text visible on the stripes?
I'm setting the font to white, and background to black. But then the text input box is white, and then on the SMS message screen everything that isn't a stripe, has a white background.
But in an HTC Theme I saw where the text inbox background was black and the background was black.