Workaround normalization behavior in Sass

Evidently in Sass, when you have a bare color name, it will normalize it so
that the name is all lowercase. We're not using it as a color name, so it
needs to be quoted to avoid this behavior.

(I didn't pick this up when I originally wrote it because I wasn't using a browser that tried to download all of the defined webfonts at once...sorry about that.)