how to reference pages in custom css or membership url groups

How do I reference a page and all pages underneath it?
For custom css as well as inside the membership url groups area.
I want to protect my members directory and everything in it, not just the main members page.
Same goes for referencing a blog done inside one of my pages. The blog is at that page and beneath, not just that one page.
What's the proper way to reference that, so membership will pick it up correctly?