It's ironic that the author chose to use a page that loads 1.5Mb of data, including 12 separate stylesheets, to write about a minimal stylesheet.
I plan to shift away from class based css frameworks myself over the next few weeks as I update my website. Of all the people who over use css frameworks like bootstrap, I'm one of them as well and this is an attempt to start correcting that mistake.
Have you had a look at https://tailwindcss.com? I'm just finishing a large redesign project using tailwind on a Rails/Vue platform and the experience has been great. The idea is that all classes are small, focussed and do one thing only. The downside is that the markup starts to look like 1995 again. The upside is the speed at which you can style a site, and the lack of mysterious hard to track bugs. I really recommend trying it for a small project, but it's not for everyone.