Symptoms
Issue: Font looked slightly different in development environment compared to the production environment when using Sharepoint 2013 theme after an upgrade to 4.6.11.
Diagnoses
Diagnosis: Links were given to community articles regarding clearing the browser cache as well as slightly modifying the font of the theme. http://community.k2.com/t5/General/SharePoint-2013-Theme-Font-Issue/td-p/81175
Resolution
Resolution: Following the link, clearing the browser cache as well as modifying the font of the theme helped fix the issue.