Not the commenter you're replying to, but on my system I see a difference between the two examples they post. This is because hackernews has font-family: Verda

Not the commenter you're replying to, but on my system I see a difference between the two examples they post. This is because hackernews has font-family: Verdana, Geneva, sans-serif and I have neither of the named fonts installed. On my system, hackernews is rendered using Dejavu Sans. This is presumably a default for Firefox on linux which I never realised until today.