[andrewmcwatters]

As far as small projects go, it's useful to take what you've learned from larger projects like Bootstrap, and use a subset of that knowledge.

For virtually everything else in production, you should be using themed Bootstrap or CSS framework x, y, or z that fits to your corporate identity. Usually so you can have a front-end engineer make decisions about symbols and have those changes flow out to the rest of your webpages and web apps without relying much on engineering to hand tune everything all over again. This is sort of ideal CSS usage, though it's probably debatable by folks here.

CSS is development more than it is design. It just helps you accomplish design.

Maybe one of the points glanced over CSS discussions is that the traditional visual formatting model was designed for documents, and not web page and web app layouts for today's world. That's better addressed by flexbox and CSS grids. For instance, the entire concept of floats isn't for aligning things, it's for text to flow around "floated" boxes like images. Most hacks like clear fixes were designed to help utilize floats for page layout versus document composition.