Thanks, JSWolf...
I gave this a shot, but it also smooshes the image horizontally in calibre, similar to the
Code:
height: 100%;
width: auto;
styling. And if the window is wider that it is tall, it isn't limited vertically in either Sigil's preview window or PageEdit.
Again, part of the issue here is that it seems that the simple
Code:
height: 100%;
width: auto;
SHOULD work in a certain straightforward way (i.e. fits any given screen up to 100% of the screen's height and automatically adjusts the width proportionately), but it doesn't, and I don't understand why not. And the fact that its idiosyncratic behavior is doubly idiosyncratic depending on whether it's being viewed in Sigil, PageEdit, or Calibre only serves to scramble my brains even further.