snapshot for default app classes

Author: willmcgugan

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed running `App.run` after `asyncio.run` https://github.com/Textualize/textual/pull/5799
 - Fixed triggering a deprecation warning in py >= 3.10 https://github.com/Textualize/textual/pull/5799
 - Fixed `Input` invalid cursor position after updating the value https://github.com/Textualize/textual/issues/5811
+- Fixed `DEFAULT_CLASSES` when applied to App
 
 ### Added
 

src/textual/app.py

@@ -565,7 +565,7 @@ def __init__(
             CssPathError: When the supplied CSS path(s) are an unexpected type.
         """
         self._start_time = perf_counter()
-        super().__init__()
+        super().__init__(classes=self.DEFAULT_CLASSES)
         self.features: frozenset[FeatureFlag] = parse_features(os.getenv("TEXTUAL", ""))
 
         self._registered_themes: dict[str, Theme] = {}