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[css3-values][css3-mediaqueries] resolution in dpi / dppx

From: Johannes Koch <koch@w3development.de>
Date: Mon, 28 Jan 2013 14:29:33 +0200
To: <www-style@w3.org>
Message-ID: <4e7836d59de66583bd8d15fb0dfc7eaf@w3development.de>

when testing mobile Opera and Firefox browsers, I encountered the 
following inconsistency:

On a device with 2 CSS pixels per device pixel, Opera Mobi 12.10 
reports a media quiery min-resolution of 2ppx or 192dpi. Firefox Mobile 
18.0 on the same device  reports a media quiery min-resolution of about 
3.3ppx or 320dpi. The device is said to have a display with 312ppi. So I 
guess, Firefox rounds 312ppi to 320dpi and calculates

320/96 ~= 3.3 (dppx)

, whereas Opera accepts the 2 CSS pixels per device pixel for 2dppx and 

2*96 = 192 (dpi)

. Is the Opera version correct and Firefox wrong, because a CSS inch is 
not the same as a physical inch?

In te domine speravi; non confundar in aeternum
(Te deum, 4th century)
Received on Monday, 28 January 2013 12:29:56 UTC

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