Mobile devices, such as smart phones, have become an important tool for content creation. Viewing or presenting content is the complement of creating it. Historically, rendering content such as music, pictures, email, and especially Web pages via mobile phones has been much more important than using a phone to create such content. Modern smart phones have a variety of media players and increasingly capable Web browsers, which are available for displaying or presenting different types of content. Phones have high-resolution color displays, stereo sound, lots of memory, and powerful processors, yet the rendering of content on mobile devices, especially Web content, still presents challenges. One major goal of the World Wide Web Consortium (W3C) has been device-independent content or as they say in the Java community, "write once, display everywhere." Decoupling layout from rendering was supposed to make it possible to easily and clearly present Web content by using different browsers running in different-sized windows on different computers with different- sized screens.