User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040707 Firefox/0.9.2 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040707 Firefox/0.9.2 It looks like that Mozilla renders a thick underline with hyperlinks and underlined text (on large text sizes). The rest of the browsers (IE & Opera.. and maybe others) do not modify the thickness of the underline, even if the underlined text is bold. You can see this behaviour on these pages: 1. http://www.google.com/search?hl=en&ie=UTF-8&q=test&btnG=Google+Search Notice how some links have the thick underline and some don't. This is because of the text size. 2. http://drudgereport.com/ You can see this problem in the headline (right above the 'Drudge Report' image). The headline is a bolded hyperlink with a bold (thick) underline. You should compare the output of those pages on several browsers, and you will see that the rendering there doesn't affect the underline. I will attach a test page that shows the scenarios. P.S. this has been a bug in Mozilla for so long ... I hope it gets fixed! Reproducible: Always Steps to Reproduce:

This shows some cases where the thick underline appears. Compare the output of the page in different browsers and see that most of them don't have that thick underline.

related/dup of bug 50410

*** This bug has been marked as a duplicate of 50410 ***