Default to auto

Author: willmcgugan

src/textual/constants.py

@@ -71,5 +71,5 @@ def get_environ_int(name: str, default: int) -> int:
 MAX_FPS: Final[int] = get_environ_int("TEXTUAL_FPS", 60)
 """Maximum frames per second for updates."""
 
-COLOR_SYSTEM: Final[str | None] = get_environ("TEXTUAL_COLOR_SYSTEM", None)
+COLOR_SYSTEM: Final[str | None] = get_environ("TEXTUAL_COLOR_SYSTEM", "auto")
 """Force color system override"""