1.1 physical pixels
Reason: minimum css style is 1px, 1px but this only represents css pixels, physical pixel high-definition display screen to be> 1 (iphone6 1css physical pixels pixels = 2 iph6p is 1css physical pixels pixels = 3.)
Solutions: If you want to show a physical pixels, can only use the zoom scale.
Method a: local scaling
which element to use a physical pixels, which element is set vertical scaling. As is 1/2 or 1/3 of the zoom screen to see the DPR (the ratio of the pixel values of independent physical device pixels) on