Apple created forks of the open-source KHTML and KJS layout and JavaScript engines from the KDE Konqueror browser in 2002. They explained that those provided a basis for easier development than other technologies by virtue of being small (fewer than 140,000 lines of code), cleanly designed, and standards-compliant. The resulting layout engine became known as WebKit and it was incorporated into the Safari browser that first shipped with Mac OS X v10.3. On June 13, 2003, Microsoft said it was discontinuing Internet Explorer on the Mac platform and on June 6, 2007, Apple released a beta version of Safari for Microsoft Windows. On April 29, 2010, Steve Jobs wrote an open letter regarding his Thoughts on Flash, and the place it would hold on Apple's iOS devices and web browsers. Web developers were tasked with updating their web sites to be mobile friendly, and while many disagreed with Steve Jobs's assessment on Adobe Flash, history would soon prove his case in point with notable mentions of poor performance of Flash on Android devices. HTML4 and CSS2 were the standard in most browsers in 2006. However, new features being added to browsers from HTML5 and CSS3 specifications were quickly making their mark by 2010, especially in the emerging mobile browser market where new ways of animating and rendering for various screen sizes were to become the norm. Accessibility would also become a key player for the mobile web.