So I sat down and went through the novel... and found more inconsistencies that would of really give calibre a good drubbing.
Here's what I ended up doing:
- Ran through all the blog post scenes and converted them from using tables to using styles.
- Found that everything was a mix of multiple styles, so exported it all to HTML.
- Stripped out all the manual styling via Visual Studio Code.
- Stripped out the fonts to the bare minimum. Really, LibreOffice, you put six fonts I don't use? I only use three.
- Corrected some weirdness (ie why did I have a list entry between two paragraphs... and bold in bolded headings...)
- Imported the HTML back into LibreOffice.
- Went through every scene again, defining custom styles to keep things consistent.
- Export it to DOCX
- Imported it into Calibre, pushing it to AZW3 format, default settings.
I'm much happier now.