For anyone interested, I figured out a way to edit the .docx output horizontal rule in Quarto. I wrote a quick lua filter based on the some of the code here and set it up to work in Quarto.
The raw code of the lua filter is here
-- Converts default grey horiztonal rule to thin black line (customizable in line 10)
-- h/t https://github.com/jgm/pandoc/issues/2573
-- h/t https://gist.github.com/Merovex/05e3216f8f4f6e965cd9d564b1496719
local horizontallinerule = [[<w:p>
<w:pPr>
<w:pStyle w:val="HorizontalRule"/>
<w:ind w:firstLine="0"/>
<w:jc w:val="center"/>
<w:pBdr>
<w:bottom w:val="single" w:color="000000"/>
</w:pBdr>
</w:pPr>
<w:r>
<w:t></w:t>
</w:r>
</w:p>]]
function HorizontalRule (elem)
if FORMAT == 'docx' then
return pandoc.RawBlock('openxml', horizontallinerule)
end
end
I also set it up to work in the _extensions file in a Quarto doc here