This fixes:
1. Sections overlapping with navbar when linked to. The fix is dirty,
it's just a margin.
2. The inability to scroll down to 'contacts' and other lower sections.
We just expand the second-to-last section to allow the browser to
scroll.
3. Updating the currently active section - this now uses a global view
of all visible sections that is updated by the observer diff, thereby
fixing the logic.
q3k
