Description
This is for comparison with the LO HTML filter export that was used previously.
XHTML filter needs a tweak because there's too many headings in the file.
https://people.freedesktop.org/~mst/body.xsl
overwrite this LO file: share/xslt/export/xhtml/body.xsl
... then, thanks to the magic of XSLT, it only takes 22 minutes to export this document on my laptop.