Coding Q&A With Chris Coyier: Responsive Sprites And Media Query Efficiency | Smashing Coding
►http://coding.smashingmagazine.com/2012/08/13/coding-qa-with-chris-coyier-responsive-sprites-responsive-f
This is a hot topic lately because of the rise in “retina” displays. But really, this problem has been building up for a while. Us Web designers often work in “pixels”, for instance, setting the width of an image: img { width: 100px; }. But what is 100px? It’s been a long time since that literally referenced a pixel on the screen. These days it’s a rather arbitrary measurement. 100px ends up being around an inch on a physical screen, regardless of its resolution.