Font Awesome (or any other webfont in production)

If you are using Twitter Bootstrap then it's likely you're also using Font Awesome. If not you need to check it out.

We ran into a problem after deploying to production that we didn't observe in development - namely that none of the Font Awesome icons would show up under Firefox. Turns you you need to configure your server to send the proper headers and allow cross domain requests. Also check out Firefox doesn't allow cross domain fonts.