css - what exactly is device pixel ratio? - Stack Overflow
In the world of web development, the device pixel ratio (also called CSS Pixel Ratio) is what determines how a device's screen resolution is interpreted by the CSS.
CSS interprets a device's resolution by the formula: device_resolution/css_pixel_ratio. For example:
Samsung Galaxy S III
Actual resolution: 720 x 1280
CSS Pixel Ratio: 2
Interpreted resolution: (720/2) x (1280/2) = 360 x 640
When viewing a web page, the CSS will think the device has a 360x640 resolution screen and Media Queries will respond as if the screen is 360x640. But the rendered elements on the screen will be twice as sharp as an actual 360x640 screen.
Mon 21 Jul 2014 03:25:37 PM CEST - permalink -
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http://stackoverflow.com/questions/8785643/what-exactly-is-device-pixel-ratio