... CTRL+F, 'compat', no results. Oh crap.

I run my blog on Bootstrap 4, and I don't have much skills for frotend/scss stuff. So I use bootstrap 4 out of the box with few customizations. I never understand the backwards compatibility model of Bootstrap. It broke significantly when I moved from some late-stage BS4 alpha to the stable version. I can probably assume it'll significantly break again? Maybe that's the beauty of BS, you just choose a version and stay there until it's impossible anymore?