I have discovered some problems with the rendering of text when a paragraph with print in normal size is followed by a paragraph with smaller print. The small print actually gets larger than the normal print.
Here are a few pictures that illustrate this.
The first picture is a screenshot from Calibre's reader, this picture shows what it ought to look like:
The next picture shows the rendering of Marvin 2, also ok.
The next one shows the result using Marvin 3, the "small" print is actually larger than the normal print.
And finally a picture using Marvin 3, but here there is chosen publisher layout, same problem