From where do editor get content to dropdown Styles?

Hi

I want to add some classes to dropdown Styles in Article Editor. But from where or what CSS do content to this get generated?
Is this not generel or do Gavick templates do some speciel?

I have tried to follow this:
http://www.crescentcitywebs.com/blog/in ... ce-editor/

Also looked at the attaced pictures.

Best regards,
Henrik

jce-editor.png

styles-list.png