I'm not a pro. I have my business web site that has grown from 5 files to 300 files. My css file is now about 800 lines long, and it's getting difficult to manage.
I've got a certain amount of cruft in it.
The firefox extension 'Dustoff' helps. It can follow a sitemap and tell me what selectors aren't used.
The W3C validity checker doesn't help. It verifies that I've got matching brackets and my options are spelled correctly.
CSS-Lint fusses at me about redefinitions. I tend to factor --
h1, h2, h3, h4 {
font-variant:small-caps;
}
h3, h4, h5, h6 {
margin: auto;
width: 35rem;
}
The idea being that stylistically related items are set in one place.
Now I'm faced with trying to make a more responsive design with two goals in mind: Have it at least usable on a phone, and make it reasonable to print. Both of these will require either multiple style sheets (bad from both speed and maintenance) or longer style sheets (just more difficult to maintain)
In terms of coding style and organization, what are current common accepted practices to make maintainable CSS files?