I had a question about the "append extra css" option.
I tried this plugin on one of my ebooks and when I looked at the css code in the Calibre edit eBooks plugin, I noticed that I had two sets of <body> and two <p> tags in my css stylesheet.
I'm using Fanfiction Downloader and that plugin has it's own css options, it appears that the append worked at adding my Calibre conversion default settings.
What I don't know is what happens when there are two sets of tags for everything but the tags have slightly different information? Though some of the tags like the headers have the exact same information.
My goal was to reference fonts I've added to my Sony PRS-T3 and update my older ebooks by adding the font family to my body tag. I didn't want to reconvert over 4000 ebooks. I thought appending the font reference to the css would cause less problems.
What makes this somewhat confusing is that I have two types of conversions, one for novels and another for fanfiction I've downloaded using FFDL plugin.