From Addons > Phox WHMCS Template > Styles Tab

Colors

Colors Schema – choose from the presets colors schema or you can use your custom colors.

Typography

• Font Family – set the font family for the template
• Headings – set the font weight and font size in (px).
• Description – set the font weight and font size in (px).
• Buttons – set the font weight and font size in (px).