Designing for a Responsive Web Means Starting with Type First
Typecast is a fantastic tool for designing your typography, and they hit the nail on the head with a content/typography first design.
Making responsiveness only about grids, responsive images and media queries is a disservice to customers and brands. It needs to be about providing readable content for any device, and that means starting with type.
An excerpt from Designing for a Responsive Web Means Starting with Type First