The Apple-originated WebKit, an underpinning of software such as the Safari web browser, has become the first public rendering engine to get a perfect Acid3 score, its developers claim. Acid3 is a test site produced by the Web Standards Project, and is used to gauge the conformity of a web browser to both standards and technologies, such as JavaScript. Most browsers fall well short of a 100/100 ranking, such as Firefox 2 -- which scores approximately 53 -- and Safari 3.1, which reaches 75.
The WebKit team notes that a perfect score does not necessarily guarantee a full pass; animation must be smooth, and in some cases errors can appear despite technical compliance. As of version r31356 of the WebKit, however, the developers believe they have achieved total accuracy. It is unknown when this might be implemented into future versions of Safari.