The PCB design has a few flaws:
First the dimension layer must be drawn with thickness of zero!
The ground fills are wider than the dimension layer. That way you can never grab the dimension layer, but only get either the bottom or the top ground fill to move.
Throw out all ballast, most of it the super big "Sparkfun" logo.
Disable all layers except for the dimension layer and move it in both axis, X and Y to get the desired dimensions.
Boncuk
Then enable top, bottom and parts layer and group the entire layout to move it into the center of the "frame".