Under the hood
Open Sans is available from Font Squirrel, Google Web Fonts, MyFonts and Typekit.
DIN is available from Fonts.com, Fontspring, MyFonts, Typekit and YouWorkForThem.
Droid Sans Mono is available from Font Squirrel, Fonts.com, MyFonts and Typekit.
Lucida Grande is available from Fonts.com and MyFonts.