Before making changes to your site, print out the settings that are being changed in case you need to return them to the original settings.
1. The Font Settings customization can be found under Appearance Font Settings
2. Adjust the appropriate fields and choose the 'Apply Style Changes' button at the bottom.
3. Any extra or updated CSS (style sheet) updates can be added to the 'Extra Style Sheet' box
4. After you make the needed changes you'll need to refresh the site cache - this activates the edits and updates the site's cascading style sheet (CSS). Editing the Public Portal can be found under Content Portals Edit Public Portal
5. Click the buttons