From cad328b2e57e87b1aed00e8645b682b10068573b Mon Sep 17 00:00:00 2001
From: Andrew Huang <ahuang@anaconda.com>
Date: Wed, 28 Feb 2024 11:01:48 -0800
Subject: [PATCH 1/2] Merge stylesheets with user input layouts

---
 panel/chat/message.py | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/panel/chat/message.py b/panel/chat/message.py
index 923d88476e..4ffee50fed 100644
--- a/panel/chat/message.py
+++ b/panel/chat/message.py
@@ -461,20 +461,18 @@ def _select_renderer(
                 contents = contents.decode("utf-8")
         return contents, renderer
 
+    def _update_stylesheets(self, obj):
+        obj.stylesheets =[
+            stylesheets for stylesheets in self._stylesheets
+            if stylesheets not in obj.stylesheets
+        ] + self._stylesheets
+        return obj
+
     def _set_params(self, obj, **params):
         """
         Set the sizing mode and height of the object.
         """
-        if hasattr(obj, "objects"):
-            params['css_classes'] = (
-                [css for css in obj.stylesheets if css not in self._stylesheets] +
-                self._stylesheets
-            )
-            for subobj in obj.objects:
-                self._set_params(subobj)
-            obj.param.update(params)
-            return
-
+        obj = self._update_stylesheets(obj)
         is_markup = isinstance(obj, HTMLBasePane) and not isinstance(obj, FileBase)
         if is_markup:
             if len(str(obj.object)) > 0:  # only show a background if there is content
@@ -498,6 +496,7 @@ def _create_panel(self, value, old=None):
         """
         if isinstance(value, Viewable):
             self._internal = False
+            value = self._update_stylesheets(value)
             return value
 
         renderer = None

From 829c01815f5a0a2fbf789f9e9536170627b8e5ab Mon Sep 17 00:00:00 2001
From: Andrew Huang <ahuang@anaconda.com>
Date: Wed, 28 Feb 2024 11:26:56 -0800
Subject: [PATCH 2/2] Add tests and fixes

---
 panel/chat/message.py            | 18 ++++++++++--------
 panel/tests/chat/test_message.py | 19 +++++++++++++++++++
 2 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/panel/chat/message.py b/panel/chat/message.py
index 4ffee50fed..fe00a0f2ed 100644
--- a/panel/chat/message.py
+++ b/panel/chat/message.py
@@ -461,18 +461,20 @@ def _select_renderer(
                 contents = contents.decode("utf-8")
         return contents, renderer
 
-    def _update_stylesheets(self, obj):
-        obj.stylesheets =[
-            stylesheets for stylesheets in self._stylesheets
-            if stylesheets not in obj.stylesheets
-        ] + self._stylesheets
-        return obj
+    def _include_stylesheets_inplace(self, obj):
+        obj.stylesheets = [
+            stylesheet for stylesheet in self._stylesheets + self.stylesheets
+            if stylesheet not in obj.stylesheets
+        ] + obj.stylesheets
+        if hasattr(obj, "objects"):
+            for o in obj.objects:
+                self._include_stylesheets_inplace(o)
 
     def _set_params(self, obj, **params):
         """
         Set the sizing mode and height of the object.
         """
-        obj = self._update_stylesheets(obj)
+        self._include_stylesheets_inplace(obj)
         is_markup = isinstance(obj, HTMLBasePane) and not isinstance(obj, FileBase)
         if is_markup:
             if len(str(obj.object)) > 0:  # only show a background if there is content
@@ -496,7 +498,7 @@ def _create_panel(self, value, old=None):
         """
         if isinstance(value, Viewable):
             self._internal = False
-            value = self._update_stylesheets(value)
+            self._include_stylesheets_inplace(value)
             return value
 
         renderer = None
diff --git a/panel/tests/chat/test_message.py b/panel/tests/chat/test_message.py
index 96759e69b8..b9fa9d9e40 100644
--- a/panel/tests/chat/test_message.py
+++ b/panel/tests/chat/test_message.py
@@ -186,6 +186,25 @@ def test_does_not_turn_widget_into_str(self):
         message = ChatMessage(object=button)
         assert message.object == button
 
+    def test_include_stylesheets_inplace_on_layouts(self):
+        message = ChatMessage(
+            Row(Markdown("Hello", css_classes=["message"]), stylesheets=["row.css"]),
+            stylesheets=["chat.css"]
+        )
+        assert message.stylesheets == ["chat.css"]
+        assert message.object.stylesheets == message._stylesheets + ["chat.css", "row.css"]
+
+        # # nested
+        message = ChatMessage(
+            Row(
+                Row(Markdown("Hello", css_classes=["message"]), stylesheets=["row2.css"]),
+                stylesheets=["row.css"]
+            ),
+            stylesheets=["chat.css"]
+        )
+        assert message.object.stylesheets == ChatMessage._stylesheets + ["chat.css", "row.css"]
+        assert message.object.objects[0].stylesheets == ChatMessage._stylesheets + ["chat.css", "row2.css"]
+
     @mpl_available
     def test_can_display_any_python_object_that_panel_can_display(self):
         # For example matplotlib figures