pre { font: inherit; }
Example: http://i.imgur.com/8TLBd.png
It doesn't work with inheritance and it also won't work if the very same selector is used. E.g. if you add:
.comment{font-family:foo}
Hence this line:
http://www.w3.org/TR/CSS2/fonts.html#font-family-prop
"Style sheet designers are encouraged to offer a generic font family as a last alternative."