How to use Class header field

Hi.
I do not get to use a class module to the header using the Header Class field on the Advanced tab in the Module Manager.
I would like to know how I include the class (eg prior space) in the Class Header field, or how to include more than one CSS class suffix in the Module field.

Thank you.

Hi

Some module positions are using a "raw" style (because of design restrictions), but in template configuration You can overwrite the style of a module position adding "gk_style" next to this module position.

To add more suffixes please simply use space.