`background-image` with file path using `\` seems to be broken in HTML when published to gh-pages

Check what revealjs is doing as this works

## {background-image="images/whr-ipynb-report-1.gif" background-size="contain" background-repeat="no-repeat"}

but not this one using \

## {background-image="images\whr-ipynb-report-1.gif" background-size="contain" background-repeat="no-repeat"}

leads to this error in browser console after quarto publish gh-pages

images%5Cwhr-ipynb-report-1.gif:1  Failed to load resource: the server responded with a status of 404 ()

%5C is not expecting so there is some escaping happening.

quarto preview locally works 🤔

So could we catch that, or prevent this - it seems to be in revealjs own processing

Maybe catch attributes in Lua and

• check for existence
• then normalize path ?