[ElMiko]

Sorry, all. Wasn't very clear in my question...

I know that in a reflowable context, I can't make fixed formatting (except as an image). And I also know that the number of lines per screen changes depending on the size of the reader and the size of the screen.

What I was wondering is, given these facts, how do you prefer formatting source text that was materially (but not critically) dependent on SOME degree of positional formatting (as in the above-attached example).

My question regarding assuming default font sizes and screen sizes, wasn't meant to suggest that there IS a default font size or screen size, merely to wonder if (like phsyical books) ebook publishers/producers do (or should) assume an "ideal" font-size and layout. Obviously, physical publishers didn't/dont' have to worry about "screen" size as a variable, but they do have to consider user reading preferences (and accessibility) in setting their font sizes, right? And then, having done so, they select a font size, knowing it is not a one-size fits all solution: some people may need to wear glasses to comfortably read their books, while others may have to buy an entirely different version that is "large-print".

Similarly, an ebook producer might design a book with an idealized font-size/screen-size in mind, or at least a range. I mean, whether you realize it or not, you already are doing it. For example, if you have a reader who sets their font size to 500%, that's potentially going to change the readability of a given book, no matter how conservatively/simply you format it. At 500%, certain words may not fit on a screen, much less fit on it while including paragraph indents, thus making distinguishing paragraphs impossible for that reader. But I also suspect that most ebook producers are not assuming that a reader will set their font size to 500% on a 3-inch-wide screen using software that doesn't incorporate hyphenation. They are idealizing (even if its a range rather than a singular value) the reader's settings.

So, to be more explicit: given the example in the first post, what kinds of margins and font sizes would you assume for the three elements in order to maximize readability? Would you, for example, maintain some kind of left/right margins on the epigraphical text? Would you maintain a spacing difference between the main heading and subheading vs subheading and epigraphical text (not to mention font size and font family)? etc., etc., etc.

(EDIT: Oh, and regarding the epub2 vs epub3, i guess my question would be do you ever assume that it would be one or the other? or do you format for the least sophisticated format? or do you format for both?)