Specify page size, margins when using --convert-to to generate docx from HTML in headless mode

[OJC]

I’m using LO to generate docx documents from HTML documents in headless mode. How can I specify the page size and page margins of the generated docx?

I’ve tried adding the @page CSS selector with size and margin rules to the HTML document. I’ve looked for options to supply to the --infilter and --convert-to options (doesn’t seem to be much documentation for these) and environment variables that might be settable via the -env option but didn’t find anything.

The command I’m using at the moment is:
soffice --headless --nolockcheck --convert-to “docx:Office Open XML Text” file.html

I’m using LO 4.3.5.2

[OJC]

Oh, and I’d like to set the font as well, this doesn’t seem to get picked up from the CSS (perhaps no CSS gets used?).