There is no Staff support for CSS editing. We have only 2 Volunteers who occasionally help with CSS editing, so we don't recommend the purchase of the upgrade to those who do not already have a moderate knowledge of CSS editing and experience with it as they must be prepared to work on their own.
Misty Look is a common theme and has been CSS edited by many. I typed "font CSS Misty Look site:en.forums.wordpress.com" into Google and here are the results > http://tinyurl.com/3wu3qpn I believe if you read those threads you may find what you need to proceed on your own. Best wishes with your editing. :)