My apologies. As donatzsky correctly assumed, I haven't checked the site on Windows for a long time. An overwhelming majority of my readers have tended to be on OS X or Linux. But thanks for letting me know. I'll make sure to test on Windows too the next time I do a design update. Cheers!
A simple fix would be to add Consolas as the first font in the list. It looks almost the same as Inconsolata, comes standard with Vista/7 and newer versions of Office (including the "Viewers"), and looks good on both Windows and Linux.
Thanks — pushed that change.
It's not just you. The code snippets use Inconsolata which, in my experience, looks splendid on Linux and absolutely crap on Windows. Presumably he never looked at his site from a Windows computer.