Try changing the insets...
lua Code:
insets = { left = 2, right = 2, top = 2, bottom = 2 }
Play with those values, until you get the border positioned where you wont... you can also do negative numbers for the inset as well. That will move the border out from its anchored position - or making it larger than the bg its attached to - Which might be what you need to do.
Example:
lua Code:
insets = { left = -2, right = -2, top = -2, bottom = -2 }