From Elliott Jay Stocks:

The basic premise is this: you use media queries to design responsive websites that adapt their layout according to browser width, and you constantly resize your browser to see how the site performs, but each time a query kicks in, there’s a harsh jump between the old styles and the new ones. Why not use some simple CSS transitions to smooth that jump by animating the resize?

via CSS transitions & media queries » Blog » Elliot Jay Stocks.