I'm no expert in webdev, but while CSS comments may be useful for maintenance and for new team members, they are also a waste of bandwidth. I'm honestly curious, what HN webdevs do with comments in CSS - do you use them, or not, or maybe have some deployment scripts that strip comments off?
Ideally, you would use a tool like less or sass to generate your css (which we don't), so your comments would be in the underlying file but not in the css given to the user.
Maybe it's useful to support the site, while it's small it's ok, wait 2 more years... We are a very Tech centric community you should expect that kind of comment from HN folks.