Tackling responsive design with a mobilefirst approach, as we have here, can take what is a great mobile site and make a highly performant desktop site but it doesn't usually work the other way around. The key to it all is the media queries and starting small first. If it works that well on a mobile with the limited processor, bandwidth, and network latency, think how amazing it will be on a machine where none of the restraints exist.
In the next chapter, we'll examine WURFL and other mobile detection methods to try and adapt existing websites and make them mobile.