A CodePen by David Sparks. Daves Divs - Move Elements on Window Resize - In responsive design sometimes the html structure requires an object to come before another object but on resize should be some where else. 

CSS doesn't always move those things the way we need. 

in this example sidebar1 needs to come after sidebar2 in tablet and mobile view

This has jokingly been called "Daves Divs"… doesn't really mean anything.