I don't think it's a good idea (I think it's opposite of that) to use not yet closed parts of css3 specification in production. I mean, it's ok as long as it works without it. This code is full of vendor specific prefixes. They only add in size and many of them doesn't have reliable fallback.
Also, these buttons look close to horrible (as in unreadable) in browsers that doesn't support all features used. I only tried quite capable Konqueror but I'm affraid what would they look like in IE7. Another thing is that this is 16kB (uncompressed). 16kB for social sharing buttons that doesn't really stand out that much (as opposed to css(2)-styled buttons) and add no extra functionality to the user.
I was aiming to mimic any existing native sign-in or UI buttons styles for the service in the hope of providing some visual familiarity for visitors who have experience with any particular provider.
The Google one borrows from their new button styles and their flat-color favicon...but it could possibly be improved. Open to design suggestions. Thanks!
Also, these buttons look close to horrible (as in unreadable) in browsers that doesn't support all features used. I only tried quite capable Konqueror but I'm affraid what would they look like in IE7. Another thing is that this is 16kB (uncompressed). 16kB for social sharing buttons that doesn't really stand out that much (as opposed to css(2)-styled buttons) and add no extra functionality to the user.
So, please, think twice before using them.