How to include css/html on all pages in a Customer Portal?

How to include css/html on all pages in a Customer Portal?

Hi all,

Im currently building a customer portal in Creator.

What the best process of adding external css styles and html so all the pages in the customer portal have the same style?

If this were a website I would create a header/footer php pages and include these on every website page. (so if I update the header file it is reflected across all the web pages).

What is Creator's equivalent to this? I know I can insert HTML snippets on each page, but if I edit the header html in one snippet, it will only change that one page rather than all pages in the portal.

Thanks