Primary site using add-on domain's styling

Need your help.

1. Installed and activated Responsive theme on site 1.
2. Installed and activated Customizr theme on site 2.
3. The Responsive theme is not installed on site2.
4. The Customizr theme is not installed on site1.
5. Site 2 is an add-on domain.
6. Site 2 displays pages with site1’s styling with the exception of the Home page.

Does anyone know why site 2’s pages are presented with site 1’s styling.

Thanks for any help you can give me.

Jerry