Fix some broken font-family CSS rules

This fixes some glitchy behavior in Chromium 27.0.1453.93 on Archlinux/Gnome 3.8.

I think what was happening was that some fonts that were rendered offscreen rendered with the default sans-serif font, but were sized as if they used the tiny default HN font, causing word overlap and unreadable text when I scrolled downwards in the comments section. Anyways, this makes all comments render with Helvetica Neue, which I think was always the intention.