So what you are asking for is documentation of this initial CSS override that Blocs provides.
Since Blocs is constantly being updated that documentation could be an ongoing challenge to keep updated. What could help is if @norm works from a commented developer version of this style sheet? If so then there are ways to automate documentation of CSS files (much like JS). Which could be useful in suppling users insight into that initial “style.css” override, or for the blocs.js file also.
But Blocs is about visual simplicity, so I’m not sure that many users want to dig into such things?