Working my way through learning FSE, I’m using this this article and wondered what to do for global styles you don’t want user control over?

Previous this would be controlled via style.css however, it seems split apart as you have styles for individual blocks as well as layout/typography etc called via the theme.json

Have I missed something or is there a json setting or style sheet that can be called within the editor as well as front end but is also not customisable via the theme editor?