How to adjust the guidelines for the reverse parking camera
 

I'm talking about the guidelines here:
https://cimg2.ibsrv.net/gimg/www.maz...4ccf1f7a6b.jpg

The left and right lines are parallel with the cars in this photo from the Mazda website.

However, in my MX-5 ND the lines are not parallel, the horizontal ones correctly indicate the distance though.

This is what my car looks like (the purple lines):
https://cimg3.ibsrv.net/gimg/www.maz...0488998fff.jpg

I'm wondering how I can adjust these so that they are correct?
Or is this correct?
I showed the dealer and they are saying it's correct, but I think they are just lazy and don't want to fix it.

It's a hassle because if I align the car according to the guidelines, the car is not parallel to the curb or you would end up in another car!