Share It - Why do I need an Internet connection?
Share It uses a hosted version of Font Awesome instead of hosted all of the files locally within the stack. The reason that this was done was for performance gains with both editing the stack as well as when its published on your website. By utilizing a CDN, your browser will be able to cache the hosted font and css files and make subsequent downloads of your webpages much faster.
There is a downside to this method. If the CDN were to go offline, then the icons within Share It woudl not be properly displayed until the CDN came back online.