Making ol.Overlay accept offset values for positioning -right or bottom-

i made 2 fiddles showing the bahaviour before and after.
the divs are named after their positioning (anchor point)! not the actual position!
before: http://jsfiddle.net/simon_seyock/ob7ggtx6/
as you can see, on div named "bottom-right" no offset at all is applied. on "bottom-center" it is only applied horizontally and on "center-right" only vertically.
after: http://jsfiddle.net/simon_seyock/sL2f3nL9/2/
all offsets are applied correctly, you could draw a straight line through the anchor points of every div.