>"A static layout will never know how to reflow itself when the window size changes; it needs code to define that behavior."
I know what you mean wrt fixed-width layouts, but want to point out that reflow is the default browser behavior in the absence of problematic markup and styling rules. That's the beauty of mobile-first RWD and progressive enhancement when done right; the starting point is just the content, full stop. The first media query is the absence of support for media queries. Then min-width rules to guide layout changes across progressively larger breakpoints.