not quite clear.. well actually on the button so
if the absolute or that the level - set relative parent and child:
margin-top: -...px; // only if the child has a fixed height, set to the half of the height of the negative Marginem (it's vertically, horizontally, use the same logic).
Even as an option rock the Flex, examples can be viewed here
In your case it is not clear why there is positioning
And what about scale is it also not clear