I've checked out the css files of some of the largest websites on the web today and one thing I've noticed is they seem to place all of their css onto a single, extremely long long. This one line is dificult to browse through (due to my computer scolling slowly due to the size of the line) and impossible to read cleanly. So my question is, why do websites place all css code onto a single line? What's the advantage of that over writing a cleaner,multililne approach? Thanks.
It could either be a personal choice, or because they want to keep things optimized. The more lines you use, the larger the file size, and thus the longer it will take to load the page, especially if you have a lot of css code.
That is either call compression, minification, or optimization. It reduces the file size by removing all the formatting, and that reduces bandwidth and loading times, but it's only worth doing on high traffic sites. There are websites that compress files, like Yahoo's YUI Compressor, and there are websites that uncompress them, like MAB Blog's CSS Uncompresor
I bet they do it so it would be more difficult for other webmasters to actually read CSS code and steal parts of it, lol.
Not only CSS but they are putting HTML as well as JavaScript on a single line as well. It's done automatically by their editor programs that compresses the downloading bandwidth and time for their users significantly for better user experience. When they need to edit it again, the code will be all expanded to normal coding alignment.