The screen on NOOK devices is 600 pixels wide by 800 pixels high. It is black/gray/white only; that's why there's a separate NOOKcolor coming out next week. The screen only has 16 shades of gray.
Since NOOK doesn't support landscape-mode reading, leaving 30 pixels on each side gives 540 pixels of width for each line. Leaving 20 pixels top and bottom would leave 760 pixels of height.
But if you're dealing with CSS, you shouldn't care. You set the margins at 30 pixels left and right, and 20 pixels top and bottom. CSS worries about how big the image is being drawn.
Would it be correct to say that Nook e-ink "translates" colors of fonts into shades of gray? And would it be correct to say that Nook ignores css borders/backgrounds?
I saw 1 or 2 ebooks where I did see boxes with simple borders, but they were more like textual interruptions (i.e., they didn't float).
I'm trying to format some kind of floating textbox which will float right. I realize that space is pretty cramped on the eink device,
I could not float it, but here's the paradox.What looks ok in Nook e-ink looks crappy in Nook for ipad and vice versa.