Every page within your website (on PeopleVine) will now contain an ID tag (the page name) and a class representing the type of page (logged in or not) on the body tag as such:

The ID tag can be used to leverage CSS (or even javascript) to manipulate the user experience.  While the class for publicPages, adminPages or customPage will allow you to target certain elements based on what part of the site they're on.  In addition, the ID on the custom pages will be unique per custom page (e.g. custom_page-1234 where 1234 is the page_no).

Happy customizing... wait, speaking of happy, did you know about HAPI?  Search for custom page overrides and you'll see how you can replace whole pages (if you're that good).