I am using the CSS only theme and changed it to all my needs (this is the purpose of this theme right?). Now the WordPress Dashboard tells me there is an update for this theme. Of course I will lose all my custom changes if I upgrade from there, so I won’t do that.

A possibility is to manually change the version of the theme, but I also don’t want to do that, the update maybe contain fixes or new classes I would like to add to my CSS too. Is there any changelog of what has been added or changed in 1.2.1? How can I add only those change to my CSS?