Hello,

There are different things you can do. For example you can use our new Conditional layouts feature which enables you a layout selection based on a macro condition. Or you can use plain macros for generating the correct link to the CSS file. You can also override the page headers in the CMSPages/PortalTemplate.aspx.cs file:

 // Init the header tags
        tags.Text = HeaderTags;

Or you can create a web part, which will change dynamically the class rendered into the page.

Hopefully this gives you some pointers where to start.

Best regards,
Boris Pocatko