I cannot revert my styles.css file to its original form

[CloudF]

I cannot seem to update my style.css file found at my blog. What kills me is that up until a few hours ago, I was able to make incremental changes to the thing (rather than using a child theme).However, I kept running into problems. For instance, I had a background image in the #main-content area. Once I updated the image (keeping the same name), it failed to show. Then I kept fiddling, trying to refine the thing. My problem is that there appears to be inconsistent behavior with editing the thing.And So:I have attempted to revert the style.css back to its original form so that I can learn - and use - the whole 'child theme' thing. Problem? I can't revert. I've gone into my FTP program, physically deleted the old styles.css file and then copied over the original.I have refreshed, tried other browsers, cleared the cache within WP, and done everything I can think of. What's more, I've ensured that the code in question...\[code\]#main-content { background-image: url(gridpaper.gif repeat; padding: 25px; background-color: 0px 0px 6px rgba(0, 0, 0, 0)}\[/code\]...includes the fact that I've put the dang 'gridpaper.gif' in a bunch of locations, just in case I'm misunderstanding the url location wrong. I just revisited the site and found that the code I showed above is not actually there. My modified version is, which I've been working like mad to revert.I've reviewed the file permissions and can confirm "666" for the styles.css file. I'm completely stymied and spent far more time on this than I should have.Thanks in advance for any help you can offer.