A media query to display different CSS based on the device pixel ratio. Standard screens have a pixel ratio of 1, retina devices have a pixel ratio greater than 1.
http://www.hongkiat.com/blog/css-retina-display/
CSS Media Queries
Get access to data on 19,697,996 websites that are Device Pixel Ratio Customers. We know of 2,000,001 live websites using Device Pixel Ratio and an additional 17,697,995 sites that used Device Pixel Ratio historically and 1,114,838 websites in the United States.
Get a list of 19,697,996 websites using Device Pixel Ratio which includes location information, hosting data, contact details, 5,031,148 currently live websites which includes 3,031,147 domains that redirect to sites in the list. 17,697,995 sites that used this technology previously and 1,114,838 websites in the United States currently using Device Pixel Ratio.