What is the best way to organize your CSS code with comments?

This is fine if you are only writing styles for a single webpage or two. If you're still kinda new to CSS and web development, just do this and see how it goes, don't worry too much how the "pros" do it. But once you begin styling an entire website, those separators -- or even bigger comment block dividers -- are going to move so many hundreds of lines away from each other that they won't be very useful and you might be a lot happier making each of those groups into separate files. Going further down the rabbit hole, this is actually one major benefit of using a pre-processor like Sass, which can combine a whole bunch of Sass "partial" files into one big CSS file on the fly, so that you can write your styles in a bunch of separate, clearly contained files that keep things really organized. Then you won't need these dividers at all. :)