diff --git a/src/resources/filters/quarto-pre/shortcodes-handlers.lua b/src/resources/filters/quarto-pre/shortcodes-handlers.lua
index 5f241cc886..f9961de308 100644
--- a/src/resources/filters/quarto-pre/shortcodes-handlers.lua
+++ b/src/resources/filters/quarto-pre/shortcodes-handlers.lua
@@ -174,12 +174,14 @@ function initShortcodeHandlers()
       end
       local images = {}
       if lightLogo then
+        local classes = brandMode == 'both' and {"light-content"} or {}
         table.insert(images, pandoc.Image(pandoc.Inlines {}, add_leading_slash(lightLogo.path), "",
-          pandoc.Attr("", {"light-content"}, {alt = lightLogo.alt})))
+          pandoc.Attr("", classes, {alt = lightLogo.alt})))
       end
       if darkLogo then
+        local classes = brandMode == 'both' and {"dark-content"} or {}
         table.insert(images, pandoc.Image(pandoc.Inlines {}, add_leading_slash(darkLogo.path), "",
-          pandoc.Attr("", {"dark-content"}, {alt = darkLogo.alt})))
+          pandoc.Attr("", classes, {alt = darkLogo.alt})))
       end
       if context == "block" then
         return pandoc.Blocks(images)
diff --git a/tests/docs/smoke-all/shortcodes/brand-logo-dark.qmd b/tests/docs/smoke-all/shortcodes/brand-logo-dark.qmd
index 5af745241c..bf26a55a6d 100644
--- a/tests/docs/smoke-all/shortcodes/brand-logo-dark.qmd
+++ b/tests/docs/smoke-all/shortcodes/brand-logo-dark.qmd
@@ -13,7 +13,7 @@ _quarto:
     html:
       ensureFileRegexMatches:
         -
-          - '<img src="\.(/|\\)moon\.png" class="dark-content.*>'
+          - '<img src="\.(/|\\)moon\.png" class="img-fluid.*>'
         - []
 ---
 
diff --git a/tests/docs/smoke-all/shortcodes/brand-logo-fallback-light.qmd b/tests/docs/smoke-all/shortcodes/brand-logo-fallback-light.qmd
index f07e25f608..11935382c6 100644
--- a/tests/docs/smoke-all/shortcodes/brand-logo-fallback-light.qmd
+++ b/tests/docs/smoke-all/shortcodes/brand-logo-fallback-light.qmd
@@ -6,26 +6,20 @@ brand:
     logo:
       small: dark-logo.png
       medium: dark-medium-logo.png
-      # No light logo specified
+      large: dark-large-logo.png
 _quarto:
   tests:
     html:
       ensureFileRegexMatches:
         - 
-          # When requesting dark mode explicitly, should get dark logo
-          - '<img src="\.(/|\\)dark-logo\.png" class="dark-content.*>'
-          # When requesting light mode explicitly (which doesn't exist), should fall back to dark logo but with light-content class
-          - '<img src="\.(/|\\)dark-logo\.png" class="light-content.*>'
-          # When requesting medium size with light mode (doesn't exist), should fall back to dark-medium with light-content class
-          - '<img src="\.(/|\\)dark-medium-logo\.png" class="light-content.*>'
+          - '<img src="\.(/|\\)dark-logo\.png" class="img-fluid.*>'
+          - '<img src="\.(/|\\)dark-medium-logo\.png" class="img-fluid.*>'
+          - '<img src="\.(/|\\)dark-large-logo\.png" class="img-fluid.*>'
         - []
 ---
 
-### Dark Logo (Dark Mode)
 {{< brand logo small dark >}}
 
-### Dark Logo (Light Mode - should fall back)
-{{< brand logo small light >}}
+{{< brand logo medium light >}}
 
-### Medium Logo (Light Mode - should fall back)
-{{< brand logo medium light >}}
\ No newline at end of file
+{{< brand logo large light >}}
\ No newline at end of file
diff --git a/tests/docs/smoke-all/shortcodes/brand-logo-fallback.qmd b/tests/docs/smoke-all/shortcodes/brand-logo-fallback.qmd
index 5098014fb8..8412728065 100644
--- a/tests/docs/smoke-all/shortcodes/brand-logo-fallback.qmd
+++ b/tests/docs/smoke-all/shortcodes/brand-logo-fallback.qmd
@@ -6,26 +6,20 @@ brand:
     logo:
       small: light-logo.png
       medium: light-medium-logo.png
-      # No dark logo specified
+      large: light-large-logo.png
 _quarto:
   tests:
     html:
       ensureFileRegexMatches:
         - 
-          # When requesting light mode explicitly, should get light logo
-          - '<img src="\.(/|\\)light-logo\.png" class="light-content.*>'
-          # When requesting dark mode explicitly (which doesn't exist), should fall back to light logo but with dark-content class
-          - '<img src="\.(/|\\)light-logo\.png" class="dark-content.*>'
-          # When requesting medium size with dark mode (doesn't exist), should fall back to light-medium with dark-content class
-          - '<img src="\.(/|\\)light-medium-logo\.png" class="dark-content.*>'
+          - '<img src="\.(/|\\)light-logo\.png" class="img-fluid.*>'
+          - '<img src="\.(/|\\)light-medium-logo\.png" class="img-fluid.*>'
+          - '<img src="\.(/|\\)light-large-logo\.png" class="img-fluid.*>'
         - []
 ---
 
-### Light Logo (Light Mode)
 {{< brand logo small light >}}
 
-### Light Logo (Dark Mode - should fall back)
-{{< brand logo small dark >}}
+{{< brand logo medium dark >}}
 
-### Medium Logo (Dark Mode - should fall back)
-{{< brand logo medium dark >}}
\ No newline at end of file
+{{< brand logo large dark >}}
\ No newline at end of file
diff --git a/tests/docs/smoke-all/shortcodes/brand-logo-light.qmd b/tests/docs/smoke-all/shortcodes/brand-logo-light.qmd
index a5103ef561..615d17396a 100644
--- a/tests/docs/smoke-all/shortcodes/brand-logo-light.qmd
+++ b/tests/docs/smoke-all/shortcodes/brand-logo-light.qmd
@@ -13,7 +13,7 @@ _quarto:
     html:
       ensureFileRegexMatches:
         -
-          - '<img src="\.(/|\\)sun\.png" class="light-content.*>'
+          - '<img src="\.(/|\\)sun\.png" class="img-fluid.*>'
         - []
 ---