If you scroll down a bit the
CSS 2 spec, it is more specific about "px":
Quote:
|
Pixel units are relative to the resolution of the viewing device, i.e., most often a computer display. If the pixel density of the output device is very different from that of a typical computer display, the user agent should rescale pixel values. It is recommended that the reference pixel be the visual angle of one pixel on a device with a pixel density of 90dpi and a distance from the reader of an arm's length.
|
But in the
CSS 2.1 spec, "px" is already defined as an absolute unit:
Quote:
|
px: pixel units — 1px is equal to 0.75pt.
|
So, yes, strictly speaking ePub 2.0.1 uses CSS 2, where "px" is not hardwired, but it's still not the device pixel. In CSS 2.1 (and I assume CSS 3 too), this was fixed to 1/96 in, which roughly agrees with the recomendation of CSS 2.