How to reset font size formatting in XML/InfoPath file with c#

Currently i am developing an medical software. Therefor i use InfoPath form template with code behind c# and MS SQL or Infomix databse was a very comfortable solution. As the complexety of the system grows i had to broaden my horizon and find some tricky solutions to achieve the surreal requirements of the client. If users change the standard size formation of an richtext field and you wish to reset the font size back to the standard formatation this method will help you. People always want everyhing flexibel, fast and automatically,... properties which are very hard to reach within a software. So someday i encountered a very hard problem which took me a long time to solve it (although, afterwards it wasn't so difficult). If someone has programmed a little bit with c# before and knows about XML formating, its not that hard to rest the font size of richtext fields. So a solution had to be found. After hours of internet surfing and testing many methods i found the best way to solve this problem.