I just spent an hour or so struggling with some changes to the CSS of this site. I just couldn’t get my changes to show up in a browser. Finally, I ran my CSS through CSSCheck and discovered that my last definition ended with a ) (right parentheses) rather than a } (right brace).  Apparently, CSS doesn’t care if you close your last statement incorrectly, but, of course, when you add a new definition at the end, CSS ignores it completely.