This is really the nuts and bolts of your ebook. This is where you determine how your recipes will display in the ereader.
In a word processor program, you create paragraph and text formats and apply them to your text to determine the formatting. XHTML has some predetermined formats but they're not particularly flexible. However, XHTML supports Cascading Style Sheets (css) that let us customize the formats and extend them in ways we find useful for our documents.
One of the things I like about epub as opposed to pdf for example is that epub is a reflowable format. This means that as my screen size changes or if I rotate my phone or tablet, the text can reflow to fit the new dimensions. Or if you prefer, you can fix the layout and text flow completely so it matches a printed page. For my purposes, I like the reflowable concept and my design will reflect that choice.
Thinking about some books I've read on my phone, here a few design choices that bothered me that I'll want to avoid at least in my own epub.
- Full justification. On a phone in portrait mode, you might get 3-6 words per line with some oddball spacing. It really interrupts the flow of reading. In English, a left justification with a "ragged right" is considered the easiest to read.
- Large Margins. The particular book I'm thinking of had about .5 inch margins top, bottom and side. Coupled with the full justification, I really disliked how this particular book was laid out. And the publisher had locked in these aspects of the design so I couldn't change it in my reader. Ereaders do support font resizing and some margin control for the most part, but is still subject to the design concepts embedded in the document.
You'll end up writing a custom .css file for your book. While there are many fine points to css, for the purposes of this group, you'll be able to work with a template we create together and that you can modify to your own preferences.