Ah! But...something's wrong - according to the documentation:
You can even put different content on even and odd pages, for example the following header template will show the title on odd pages and the author on even pages:
<header style="justify-content: flex-end">
<div class="even-page">_AUTHOR_</div>
<div class="odd-page"><i>_TITLE_</i></div>
</header>
calibre will automatically replace _TITLE_ and _AUTHOR_ with the title and author of the document being converted. Setting justify-content to flex-end will cause the text to be right aligned.
BUT! Using that very code there put everything at the left?
So! Please if I could re-request my request. Below was a SWEET kind of header that worked once for me, and for a long time. How can I apply it again? What should the code look like?
pdf_header_template: u'<header style="justify-content: flex-end; color: gray; font-size: x-small">\n <div class="even-page">_AUTHOR_</div>\n <div class="odd-page"><i>_SECTION_</i></div>\n</header>'
pdf_footer_template: u'<p style="text-align:center; color: gray; font-size: x-small"> _PAGENUM_</p>'