[rashkae]

You can't really convert pt to em though.. the absolute size of em will scale with the base font size... pt does not.

Using pt, or in, is useful when you want indents to line up regardless of font size.

On the H2O, I can confirm that 1in, or 72pt (which should also be 1 inch) both come out to somewhere around .5 in on the Kepub reader. The inch is measured out almost perectly on the epub reader, so the device knows it's own DPI. This is clearly a bug/feature of the Kepup rendering.

I really have no idea what's up with your observation of having to power off the kobo to make changes. I've *never* seen that problem. Although, since the Calibre Kobo driver goes out of it's way to prevent the Kobo from detecting when a book file has changed, I almost always delete a book directly off the kobo device itself before connecting usb to replace it.