I'm assuming the various forms of page_styles.css I'm seeing (page_styles.css, page_styles1.css and page_styles3.css) in my epubs are there from Calibre's conversion process since they're present in every file. Purely out of curiosity, I'm wondering why they're their at all. Invariably, all that's in those files is:
Code:
@page { margin-top: 0; margin-left: 0; margin-right: 0; margin-bottom: 0; }
and that same bit of styling is also right at the top of stylesheet.css (which is, in general, where all the actual styling information is).