Given a bit of CSS like this
.className {
background-image: url('{!URLFOR($Resource.images)}/desired_image.png');
}
the closing paren after $Resource.images is detected as matching the opening paren for url(), which screws up syntax highlighting for the rest of the file.
Tested with jEdit 4.5.
This is fixed, I don't know when, probably the patch from Marc Häfner in December, 2012.