UI.X uses a relative font size feature that allows the users to individually increase or decrease the base font size across the site. In order for this to work as intended, all font size style properties must be set using REM and not PX. UI.X has set the effective base font to 10px, so 10px = 1rem for easy conversions. Similiarly, 16px = 1.6rem.
Google Fonts - Choose which fonts you wanted loaded from the Google Fonts API.
Secondary Font - This font family is used for headings and other decorative text situations.
Heading font weight regular - Normal font weight for all text using Secondary font.
Heading font weight (heavy) - Bold font weight for all text using Secondary font.