why use negative margins?

Question

Just looking at some CSS here, and I noticed:

.head{position:relative;overflow:hidden;margin:-30px 0 0 -25px;width:820px;padding:20px 25px 0 25px;background:         


        

Answer 1

Actually i think there is an use case where negative margins are the only right thing to do:

You want an part of a box to extend over the whole parent, even over the padding. So instead of removing the padding of the parent element an apply it to all children exept for your special case, you give your special case a negative margin. Also no haggling with positioning. Works great and is very readable.

Example: http://codepen.io/anon/pen/DpHvu