Google rolled out a new design across many of their services as part of the Google+ launch. The new look presents a sleeker, simplified Google that puts the emphasis on your data and not on the interface.
Part of the design’s success are the new Google buttons. Great UIs tend to have simple, obvious buttons that are standard across the entire application.
Google’s new look features some pretty slick buttons, as seen in Gmail’s new UI.
These buttons are built entirely in CSS, with an image sprite for the highlight buttons. Whatever your preference for buttons is, being consistent and making buttons obvious are imperative. You can easily adjust these to meet your needs or fit your designs.