A few people have mentioned that they can't post a newly created stylesheet to their blogs.
I suspect eBay has added some filters to prevent people from adding HTML codes to the stylesheet area. Since brackets are required for HTML, it sounds like eBay is taking the easy path and is filtering out brackets.
That should eliminate all the miscreant codes that have been finding their way into stylesheets. However, it looks like eBay didn't think it through because some of the stylesheet codes include legitimate brackets.
So if your stylesheet won't post, scan through the code and look for the five lines that start with:
html>body
Eliminate the entire line in all five places. It will have a small effect on the appearance of your template, but it is the only way to get past eBay's filters for the moment.
When eBay fixes the problem, you can put the unaltered stylesheet in place instead.
For those of you having difficulty, let me know if this solution works for you.