[EbokJunkie]

@kentmatt

Calibre reshuffles and renames all classes from the source file. That's why the batch file above first implements Calibre conversion epub->epub and the allows user to go thru the html code and determine what CSS class Calibre assigned to base text.
User pinpoints the correct class and sets margins in class definition.
After this we cannot allow Calibre to mess with the code; ones the negative margins are set for the correct class we call kindlegen for actual conversion to mobi (and extract azw3 from combo mobi after this).
Kindlegen doesn't mess with source classes as Calibre does.
Of course, you can just call kindlegen, feed it with html (properly referencing your css with negative margins) and you'll see expected result at any Kindle model.

BTW, it should suffice to apply negative margins to one (paragraph) class only.