test fix

src/textual/css/parse.py

@@ -347,7 +347,7 @@ def parse(
         path (str): Path to the CSS
         variables (dict[str, str]): Substitution variables to substitute tokens for.
         is_default_rules (bool): True if the rules we're extracting are
-            default (i.e. in Widget.CSS) rules. False if they're from user defined CSS.
+            default (i.e. in Widget.DEFAULT_CSS) rules. False if they're from user defined CSS.
     """
     variable_tokens = tokenize_values(variables or {})
     tokens = iter(substitute_references(tokenize(css, path), variable_tokens))

src/textual/css/stylesheet.py

@@ -209,7 +209,7 @@ class Stylesheet:
             css (str): String containing Textual CSS.
             path (str | PurePath): Path to CSS or unique identifier
             is_default_rules (bool): True if the rules we're extracting are
-                default (i.e. in Widget.CSS) rules. False if they're from user defined CSS.
+                default (i.e. in Widget.DEFAULT_CSS) rules. False if they're from user defined CSS.
 
         Raises:
             StylesheetError: If the CSS is invalid.

tests/css/test_stylesheet.py

@@ -112,10 +112,12 @@ def test_stylesheet_apply_user_css_over_widget_css():
     node.add_class("a")
 
     stylesheet = _make_user_stylesheet(user_css)
-    stylesheet.add_source(MyWidget.CSS, "widget.py:MyWidget", is_default_css=True)
+    stylesheet.add_source(
+        MyWidget.DEFAULT_CSS, "widget.py:MyWidget", is_default_css=True
+    )
     stylesheet.apply(node)
 
-    # The node is red because user CSS overrides Widget.CSS
+    # The node is red because user CSS overrides Widget.DEFAULT_CSS
     assert node.styles.color == Color(255, 0, 0)
     # The background colour defined in the Widget still applies, since user CSS doesn't override it
     assert node.styles.background == Color(0, 255, 0)