Hi Peter
This can happen if you opening your CSS files from a Unix. There are line-breaks, however different operating systems recognise different sequences for line-breaks.
Notepad only recognises CR, LF (0x0d, 0x0a), whereas other sources might use CR only, or LF only
One simple way to fix the line-feeds is to copy and paste the text into Word, then back again into notepad, and the line-feeds will get "corrected" to the CR,LF sequence.
Alternatively use a dedicated CSS editor to open your CSS files. InType (
http://inotai.com/intype/) is a great free editor (very light) that we often use ourselves.
Ciarán