(This seems to be my 'Listen to Hitch" day

)
Take some time and 'smell the code'

side of an EPUB you like the look of.
For most part (the main body of text), the basic novel, the code is really simple to style. ((this is called: 'Reverse Engineering" in my real line of work)) I was shocked, when I looked at the code of some of the early books from the "Baen Free Library". "That's it?" about a dozen lines in the style sheet(s) for the novel
All most need, is styles for :
First Paragraph
Subsequent paragraphs
New Scene (scene break treatment)
The trickier stuff is rare:
stuff like:
News Headlines
Signs
Handwritten notes or letters
Even that, usually is just another, simple style.
The fun (and this is where I like to play), is Chapter Headings. I like to give the a bit of uniqueness. That is NOT required. You could jus make them bold or a little bigger font (but that is booooring

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