Your not going to tell us?
No, I'm not. It's not my trade secret to give, really. I will tell you it has nothing to do with alterations of the border thickness.
A clue - have you ever seen a really BLACK deck with an intricate back design, but the whole thing ends up muddy-looking and the black doesn't evenly cover the white surface of the deck sheet?
I shouldn't have even given up that much - please keep speculations to yourself rather than posting them here out of respect for the designer.