Change section background color and other attributes in Basil template (7.1)

Please advise: I cannot share the site due to it being a re-build in a new template within my existing live site.

I'm trying to work out how to change the background color of a section, make it full-width, etc. in the Basil template. Not sure if I'm missing something, but it seems that in this and some templates, adding a 'section' to a page is not possible, so I've been building pages with blocks (I have also built pages with an index page and sections, which gives me control over this, but I can't nest those pages in the nav menu so I don't think that's possible in the example).

So, I'm curious if anyone can explain the best practice to make an entire section with multiple blocks, etc. a different color from other sections in the page? Please see example screenshots showing the section in question, block ids and some code from the page. Any ideas?

You can duplicate the site, set live template there, then share duplicated site url, we can check problem easier