backslashes need to be doubled for windows image paths

Author: gordonwoodhull

src/resources/filters/quarto-post/typst-brand-yaml.lua

@@ -289,6 +289,9 @@ function render_typst_brand_yaml()
           if _quarto.modules.mediabag.should_mediabag(imageFilename) then
             imageFilename = _quarto.modules.mediabag.resolved_url_cache[logoOptions.path] or _quarto.modules.mediabag.fetch_and_store_image(logoOptions.path)
             imageFilename = _quarto.modules.mediabag.write_mediabag_entry(imageFilename) or imageFilename
+          else
+            -- backslashes need to be doubled for Windows
+            imageFilename = string.gsub(imageFilename, '\\', '\\\\')
           end
           quarto.doc.include_text('in-header',
             '#set page(background: align(' .. logoOptions.location .. ', box(inset: ' .. inset .. ', image("' .. imageFilename .. '", width: ' .. logoOptions.width .. altProp .. '))))')