I believe that the ideal way to build responsive web pages and web-based applications is 'offline first'. This approach means that websites and applications will continue to work and load, even without an Internet connection.
HTML5 offline web applications (http://www.w3.org/TR/2011/WD-html5-20110525/offline.html) were specified to meet this aim.
Although support for offline web applications is good (http://caniuse.com/#feat=offline-apps), sadly, it's an imperfect solution. Although it's relatively simple to set up, there are a number of limitations and pitfalls. Documenting them all here is beyond the scope of this book. Instead I would recommend reading the humorous and thorough post by Jake Archibald on the subject at http://alistapart.com/article/application-cache-is-a-douchebag.
I'm therefore of the opinion that while it's possible to achieve offline first experiences using offline web applications (a good tutorial of how to do so is at http://diveintohtml5...