Unfortunately, they do.
But here is what would happen in practically every other e-reader except Marvin (definitely on a Kindle device or in the Kindle app): in that book with oversized fonts, you would decrease your font. But then, returning to the first book, the font would be too
small there. Again, resize needed. Returning to the second book, yet another resize needed. It's an endless run-around, back and forth, back and forth. I loved using Stanza for many years, but this (among other things) used to drive me crazy about Stanza.
None of the above is ever an issue in Marvin. You set your preferred font size in each particular book
once, and it
sticks.
In fact, if you ask me, I find it preferable
not to use the
same font size in all of my books. Depending on the type of book (fiction? non-fiction? easy to read? difficult to read? lots of dialogue? long paragraphs? short paragraphs?), I may find
various font sizes preferable for various books.
The beauty of Marvin is it allows you to customize the typesetting for every
individual book you ever open in Marvin, whereas all other e-readers insist on treating
all e-books in the
same way --
without, however, achieving any sort of visually pleasing uniformity by proceeding in such a "despotic" manner.
Nope, the actual result of
treating all e-books in the same way is, ironically, that they
all look different then -- but unlike in Marvin, there is no easy way to remove that unavoidable
initial disparity (and make it stick!), in those other e-readers.