Facing the similar issue with Office2007 skin after upgrading (from 2011) to 2015 Q3. The font family and size of the body CSS is getting overridden with Radsplitter CSS.
body{ font-size: 12px; font-family: Arial, Helvetica, sans-serif; }Also I tried replacing the body CSS with body id and class but still its getting overridden by Radsplitter css in both the cases. Please suggest how to fix this.