how to customize part of the site ?

Hello,

I want to change the presentation of different parts of my site. So I tried to use a copy of the template gk_corporate2 assigned to certain menu items.

Now unfortunately I can not establish the needed changes in the css because finally I only have one css file, that of the original template, gk_corporate2.

How to duplicate the style sheets?

How to assign a particular style to certain pages?

I tried using suffixes page but I do not understand how does it work.

Thank you for your clarification.

Sincerely,