Dewayne dug up this old Bryan Bell post about CSS and Radio:

If you would like to centralize your Radio CSS you can simple save your Style sheet as “#cascadingStyleSheet.txt” then place it in your “www” folder. Then simply add the macro to your template. Your CSS will be included where you included your macro.

This method will work even if you create a theme out of your design.

Spaces in the CSS macro tag added by me to prevent Radio from being confused…

I'm glad I found this. I'm working on my test install of Frontier/Manila and need this info to build the “surprise”.