I have implemented "nice titles" (styles the popup when you hover on a link) CSS in a test blog. Both the script and the style sheet are imported into the pages.
The test blog can be viewed [url]http//cranialcavity.net/testblog/index.php]here[/url]
I have used this script before with no browser problems.
If you desire you can Email me here , or leave a comment on the test blog.