Or just see if your favorite editor has a folding mode.
.selected {
color:white;
}
into .selected{}or .selected { color:white; }?
Most folding modes that I've seen makes the block hidden, which is nothing like what single line CSS is.
But really, if you plan your CSS instead of applying edge-case band-aid over edge-case band-aid, this becomes a complete non-issue.
And also question why you have 1000+ lines of CSS.
news.ycombinator uses only 31 selectors. And it looks.. well maybe not great , but very readable and very useable (I like it a lot).
And I think it's better to have more classes defined in your DOM-object than doing the same stuff multiple times. I mean, most of the time widths, margins and paddings are reusable. So why not create classes for them.