What is a reference pixel and arm length reader?

Question

Machine translation from one language to another

https://developer.mozilla.org/en/docs/Mozilla/Mobi...

If the pixel density of the output device is very different from that of a typical computer display, the user agent must scale the pixel values. It is recommended that a block of pixels refer to all the number of device pixels that best approximate the reference pixel. It is recommended that the reference pixel be the angle of view of one pixel on a device with a pixel density of 96dpi and an arm's length distance from the reader.
For web developers, this means that the page size is much smaller than the actual number of pixels, and browsers can change their layouts and images accordingly. But remember that not all mobile devices are the same width; You need to make sure that your pages work well with large changes in screen size and orientation.
The default pixel ratio depends on the density of the display. On a display with density less than 200 dpi, the ratio is 1.0. On displays with densities between 200 and 300 dpi, the ratio is 1.5. For displays over 300 dpi, the ratio is the whole floor (density / 150 dpi). Note that the default ratio is true only when the viewport scale is 1. Otherwise, the ratio between CSS pixels and device pixels depends on the current zoom level.

Answer 1

hit the left kidney twice quickly - launch a subpoena
, that's what "distance from the arm length reader" is! ..