CSS expert. Convert to Responsive Design (Mobile)

I have a single HTML page that I need to be converted to a responsive design. When I am done completing the rest of the page I will port this to PhoneGap for a native phone app. YOUR JOB: Convert my HTML to a responsive design so that it can be easily viewed on all mobile devices. You need to keep in mind that the main goal will be for me to port this to a PhoneGap native application.