It was right in the initial talk about how to do RWD - you start with a design and then scale your browser and fix it at the widths it "breaks" at (stops lookin

It was right in the initial talk about how to do RWD - you start with a design and then scale your browser and fix it at the widths it "breaks" at (stops looking aesthetically pleasing). Unfortunately, that tends to require more effort than just creating a list of media queries based on common device sizes and only worrying about those.