Jhana UI uses CSS variables, so you can configure your fonts however you need, or just use the included fonts.
You can use your own font-face, if you set those variables at the theme-root level. Ideally, your font is
variable and supports the `wght` and `opsz` variation settings, as well as the `tnum` feature setting. You can
inject your own variable font configurations as well.
For reference, this is how Jhana implements its included font stylesheets.