As we are bringing more flexibility in the definition of themes with Style Books, we also would like to enable importing them as a file (JSON). The site theme for both public and private pages will have a base theme associated and beside it
Given a UX Designer has prepared a ZIP file made of structured CSS variables (Style Book) and custom CSS file, page templates and fragments (JSON definitions and html)
When a theme developer is deploying the ZIP made of StyleBook+Fragments+PageTemplates+Custom CSS style
Then the StyleBook+Fragments+PageTemplates are deployed to the given Site and associated to the corresponding base theme.