I am on Ubuntu 12.10 (using firefox, but the same font appears on chrome too) and I've been changing the theme and fonts of the system using ubuntu tweak tool.
The problem is that the code segments at the questions/replies now use the Monaco font while the code segment at the comments use the classic font used here (I think it's Ubuntu Mono).
Here is how it looks:

How can I make all the code segments use the classic Ubuntu Mono font?
...sections of the page. If this doesn't work, It may be worth asking on the Stack Exchange website what HTML tags are used. – SimplySimon Sep 10 '13 at 16:43