The first version was only planned to give people a more comfortable use for theming tokens in SPFx projects. Today I released a new version that improves the typography in a way that Office UI Fabric currently not provides.
This new release is mainly targeted for accessibility and gives the ability to define custom classes based on the outlined typography.
A while back I wrote about on how to use the theme slots in the SPFx projects through SASS. It allows you to write web parts that reflect the default theme colours of a site. Instead, using fixed colour values, you can use variables in the CSS code of your artefacts.
To make the overall process faster I recently released and NPM packages including all the SASS colours plus some extras.