Slight Linearity is acceptable, but its conditional upon the Possibility of Modification or vice versa. (For example some Sigs show Gaming Stats directly update-able from a particular website, some BF3 sigs for instance)
In your case, I cant do anything other than ask you to change it.
Your signature is removed. Upload it once you have fixed the height.
As for leaving PG, you can stay or leave. Its not my problem. As long as you are here, you'll have to follow the rules.