(see the discussion at Smaller font size needed for page numbers)
If I understand correctly, customCollectionStyles.css provides a way to customize various formatting defaults for a collection. customBookStyles.css does the same thing for an individual book. JH writes, “If you want to have these different page number sizes follow the book as you share it with others as a shell, you don’t want the rule in customCollectionStyles.css. Instead, create a file named customBookStyles.css in the book folder, and place the rule in that file.”
In my Source Collection I want all the books I create to have uniform formatting, so logically I should use customCollectionStyles.css. But I definitely do want my custom formatting to follow the books as shared shells. It would be nice to have the current customCollectionStyles.css automatically copied into each new book folder as customBookStyles.css. Then, of course I can override this for a particular book in the collection by editing customBookStyles.css.
My reason for asking this is more important than my own tendency to forget details such as manually copying a file to each new book. It will be very difficult to pass on the need for this manual tweak to any other editors of my Source Collection, either current or future users.