Board Thread:Support Requests - Designing Your Wikia/@comment-1853717-20140313185130/@comment-1997905-20140313192626

positions an element explicitly relative to its first parent that is also positioned explicitly.

Or more simply, if you have: Then,  , etc. on   will be relative to  , not  , because   is first parent of   that is explicitly positioned. If you instead had: Then,  , etc. on   will be relative to  , because   is the first parent of   that is explicitly positioned. is the same as  in that it lets you use ,  , etc., but with   the element keeps its normal location, instead of being stuck at the top left hand corner of its first absolute parent.