more fixes to scroll offset for the sticky header.

This offsets the layout position of all <a name=""> tags so they naturally
show up below the sticky nav bar... though this is only for API reference,
which uses <a> tags as anchors for all API members.
bug: 16924057

Change-Id: I88c1e8192f1cbb5373af592b9e9f9a04ffe6fc7c