RC4 custom edits

Where should I make my changes to the pda and iPhone templates in order for them to not be overwritten upon future installs of MJ? I've already started to make some changes to mj_xhtml.css... was this a mistake and if so, how can I just roll back to a fresh install of RC4? Thanks very much!

There is special file for custom changes: css/custom.css
It is loaded last, so allows you to override any previous css styles.

Awesome! Thanks for your help.