What does "inverted" in "Hair line should be inverted" mean?

Well, the way I have heard inverted used is with hairstyles such as an inverted bob. Something that is inverted means there is a reverse in position or it is going in a different direction than the norm. For instance, an inverted bob means someone has short hair that is shorter in the back and then goes longer as it heads toward the front. So, basically, anything that is cut or growing in a direction contrary to what is the norm, or backwards. Here is a picture of an inverted bob to give you an idea of inversion:

http://www.stylist225.com/uploads/8/3/3/8/833856/5...

Long Reverse Bob