I'm new to this SE site, but I noticed some inconsistency in the way that 'tabs' are styled on this site.
Here's a screenshot from the questions list:
And most other areas of the site look very much like this. However, on any user profile page, there's some extra padding between the tabs and the line below them:
Note that this may be observed on the main site and on the meta site. I'm not sure if this was intentional or not, but it looks like a bug to me. I think it should at least be consistent across the site.