According to Firebug, the code examples are set in Lucida Console, ​Monaco, or ​monospace, in that order of preference. I don't believe that Lucida Console or

According to Firebug, the code examples are set in Lucida Console, ​Monaco, or ​monospace, in that order of preference. I don't believe that Lucida Console or Monaco is a terribly good face, but neither of them exhibits the behaviour you report, so it's probably a problem with your browser font configuration. I currently recommend Source Code Pro for monospace, Linux Libertine for serif and Linux Biolinum for sans-serif. These are the most attractive & legible fonts I've yet found for day-to-day use, but I'm glad to hear of others' findings.