This document provides an overview of responsive design using HTML5, CSS3, JavaScript, and the Backbone.js framework. It discusses the rise of JavaScript frameworks like Backbone and how Backbone can be used for responsive design. It then explains the concepts of responsive design, including flexible grids, media queries, and avoiding fixed widths. It also discusses using HTML5 features like pushState to support responsive design goals. Finally, it gives a high-level overview of how to structure a Backbone application to support responsive design.