[nerbert]

I don't think there's any alternative to editing editor.css. The CK Editor imports or pulls in (if that's the right term) the editor.css template. If you want another css file to override it it would take a plugin to concatenate it into the list. I don't know if you want a plugin in a style package but I think I can get it going if you want to add another css file as a template.

See line 122 vb/ckeditor.php. I've added more css by concatenation in the editor_construct hook. I think I can get it working. But the bottom line is nothing in additional.css will affect the editor