The standard buttons provided by third parties (such as Facebook, Twitter and SoundCloud) vary in size, style and interactivity. A consistent button set could reduce a lot of that visual noise and inconsistency. Furthermore, having it in CSS format means that changing the text for certain actions would be a breeze for developers, and it also allows administrators of non-English websites to translate labels into their native languages.
The button set was designed from the beginning to require no extra markup, and the elements used are entirely the choice of the (semantically considerate) designer. All buttons are fully scalable and customizable, and they degrade gracefully on older browsers, although the aesthetics in IE 6 and 7 are admittedly inferior to image-based alternatives.

Pears is an open source WordPress theme, enabling people like you to get your own pattern library up and running quickly.