I've implemented Bootstrap 4 CSS & JS into my Magento 2.2 site via a module, and now I'd like to start adding classes like .container, .row, .col-md-6, etc etc., to the various aspects of the site.
How and where in the world do I do this at? Searching through the code isn't really doing me any favors. The big goal with doing this is to leverage the various classes that Bootstrap 4 already has, to build a more cohesive front end experience for the end user, and for front end developers moving forward to have an easier time.
For example, I'm looking at the home page to my store and it just has a small grid of products on it. I'd like to apply bootstrap 4 classes to first, the overall content container (maincontent I think it's called? using simply the .container class), and then to apply column classes (.col-md-4 for example) to the product grid boxes themselves.