verbatim/css_browser_selector — pull request #1 by Gutem (2013-07-04 20:02:48+00:00)
Title: Retina/non-retina classes

Added function to identify (non-)retina display and add the respective classes.
function uses window.devicePixelRatio > 1; as identifying method.

http://briancray.com/posts/detect-retina-displays-with-javascript