typing extensions import

src/textual/css/_help_text.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 from dataclasses import dataclass
 from typing import Iterable, Sequence
 
-from typing import Literal
+from typing_extensions import Literal
 
 from ..color import ColorParseError
 from ._help_renderables import Example, Bullet, HelpText

src/textual/features.py

@@ -1,6 +1,8 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Literal, cast
+from typing import TYPE_CHECKING, cast
+
+from typing_extensions import Literal
 
 if TYPE_CHECKING:
     from typing_extensions import Final