diff --git a/CHANGELOG.md b/CHANGELOG.md
index e554e03b9f..e087ec8eca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Improved rendering of Markdown tables (replace Rich table with grid) which allows text selection https://github.com/Textualize/textual/pull/5962
 - Change look of command palette, to drop accented borders https://github.com/Textualize/textual/pull/5966
 
+### Removed
+
+- Breaking change: Removed `Markdown.code_dark_theme`, `Markdown.code_light_theme`, `Markdown.code_indent_guides` which are no longer needed with the new code fence. https://github.com/Textualize/textual/pull/5967
+
 ## [4.0.0] - 2025-07-12
 
 ### Fixed
diff --git a/src/textual/widgets/_markdown.py b/src/textual/widgets/_markdown.py
index 4e4eb9f994..af9bff7c7a 100644
--- a/src/textual/widgets/_markdown.py
+++ b/src/textual/widgets/_markdown.py
@@ -802,11 +802,6 @@ def __init__(self, markdown: Markdown, code: str, lexer: str) -> None:
         super().__init__(markdown)
         self.code = code
         self.lexer = lexer
-        self.theme = (
-            self._markdown.code_dark_theme
-            if self.app.current_theme.dark
-            else self._markdown.code_light_theme
-        )
         code_content = highlight(self.code, language=lexer)
         self.set_content(code_content)
 
@@ -872,15 +867,6 @@ class Markdown(Widget):
 
     BULLETS = ["\u25cf ", "▪ ", "‣ ", "• ", "⭑ "]
 
-    code_dark_theme: reactive[str] = reactive("material")
-    """The theme to use for code blocks when the App theme is dark."""
-
-    code_light_theme: reactive[str] = reactive("material-light")
-    """The theme to use for code blocks when the App theme is light."""
-
-    code_indent_guides: reactive[bool] = reactive(True)
-    """Should code fences display indent guides?"""
-
     def __init__(
         self,
         markdown: str | None = None,
@@ -1033,18 +1019,6 @@ def on_markdown_link_clicked(self, event: LinkClicked) -> None:
         if self._open_links:
             self.app.open_url(event.href)
 
-    def _watch_code_dark_theme(self) -> None:
-        """React to the dark theme being changed."""
-        if self.app.current_theme.dark:
-            for block in self.query(MarkdownFence):
-                block._retheme()
-
-    def _watch_code_light_theme(self) -> None:
-        """React to the light theme being changed."""
-        if not self.app.current_theme.dark:
-            for block in self.query(MarkdownFence):
-                block._retheme()
-
     @staticmethod
     def sanitize_location(location: str) -> tuple[Path, str]:
         """Given a location, break out the path and any anchor.
@@ -1436,8 +1410,6 @@ class MarkdownViewer(VerticalScroll, can_focus=False, can_focus_children=True):
 
     show_table_of_contents = reactive(True)
     """Show the table of contents?"""
-    code_indent_guides: reactive[bool] = reactive(True)
-    """Should code fences display indent guides?"""
     top_block = reactive("")
 
     navigator: var[Navigator] = var(Navigator)
@@ -1521,7 +1493,7 @@ def compose(self) -> ComposeResult:
             parser_factory=self._parser_factory, open_links=self._open_links
         )
         markdown.can_focus = True
-        yield markdown.data_bind(MarkdownViewer.code_indent_guides)
+        yield markdown
         yield MarkdownTableOfContents(markdown)
 
     def _on_markdown_table_of_contents_updated(