Box-shadow Implementing a mobile (retina) ultra-fine border

//box- Shadow projection Direction // on box-shadow:  inset 0px 1px 0px 0px #000//  right box-shadow:  inset-1px 0px 0px 0p x #000; // under box-shadow:  inset 0px-1px 0px 0px #000; // left Box-shadow:  inset 1px 0px 0px 0px #000;

The effect is as follows:

Because 1px in CSS is not equal to the 1px of a mobile device, these are different pixel densities due to different phones.

There is a Devicepixelratio property in the Window object that reflects the pixels in the CSS to the pixel ratio of the device.

The official definition of devicepixelratio is the proportion of device physical pixels and device independent pixels, i.e. Devicepixelratio = physical pixels/independent pixels.

More workarounds See: http://www.jianshu.com/p/7e63f5a32636

Box-shadow Implementing a mobile (retina) ultra-fine border