Here are some resources for how to host fonts with Github:
To set the fonts in Super use this CSS to set the primary (headings) font and the secondary (body text) font:
:root {
--primary-font: FONTNAME, FALLBACK-FONTNAME !important;
--secondary-font: FONTNAME, FALLBACK-FONTNAME !important;
}
The fallback fonts can be as generic or specific as you like. At a minimum use serif or sans-serif as the fallbacks as approapriate.
Note that these fonts will be accessible for others to download and this method is not recommended for purchased proprietary fonts.