diff --git a/solitaire_data/src/settings.rs b/solitaire_data/src/settings.rs
index 391c93c..c7e47ea 100644
--- a/solitaire_data/src/settings.rs
+++ b/solitaire_data/src/settings.rs
@@ -143,10 +143,10 @@ pub struct Settings {
     #[serde(default)]
     pub window_geometry: Option<WindowGeometry>,
     /// Identifier of the active card-art theme. Matches `meta.id` from
-    /// the theme's `theme.ron` manifest. `"classic"` and `"dark"` are
+    /// the theme's `theme.ron` manifest. `"dark"` and `"classic"` are
     /// always present; user-supplied themes register under their own ids.
-    /// Older `settings.json` files that stored `"default"` will fall
-    /// back to the dark embedded theme at runtime.
+    /// Older `settings.json` files that stored `"default"` or `"classic"`
+    /// are migrated to `"dark"` by [`Settings::sanitized`].
     #[serde(default = "default_theme_id")]
     pub selected_theme_id: String,
     /// Set to `true` once the achievement-onboarding info-toast has been
@@ -272,7 +272,7 @@ fn default_music_volume() -> f32 {
 }
 
 fn default_theme_id() -> String {
-    "classic".to_string()
+    "dark".to_string()
 }
 
 /// Default tooltip-hover dwell delay in seconds. Mirrors
@@ -395,6 +395,13 @@ impl Settings {
     /// their respective ranges after deserialization or hand-editing of
     /// `settings.json`.
     pub fn sanitized(self) -> Self {
+        // Migrate stale theme IDs: "default" was removed when the theme was
+        // renamed to "dark"; "classic" was briefly the default before "dark"
+        // was restored as the shipped default.
+        let selected_theme_id = match self.selected_theme_id.as_str() {
+            "default" | "classic" => "dark".to_string(),
+            _ => self.selected_theme_id,
+        };
         Self {
             sfx_volume: self.sfx_volume.clamp(0.0, 1.0),
             music_volume: self.music_volume.clamp(0.0, 1.0),
@@ -407,6 +414,7 @@ impl Settings {
             replay_move_interval_secs: self
                 .replay_move_interval_secs
                 .clamp(REPLAY_MOVE_INTERVAL_MIN_SECS, REPLAY_MOVE_INTERVAL_MAX_SECS),
+            selected_theme_id,
             ..self
         }
     }
diff --git a/solitaire_engine/src/theme/registry.rs b/solitaire_engine/src/theme/registry.rs
index 3c32316..918a859 100644
--- a/solitaire_engine/src/theme/registry.rs
+++ b/solitaire_engine/src/theme/registry.rs
@@ -100,8 +100,8 @@ fn build_registry_on_startup(mut registry: bevy::ecs::system::ResMut<ThemeRegist
 /// [`user_theme_dir`].
 pub fn build_registry(user_dir: &Path) -> ThemeRegistry {
     let mut entries = Vec::new();
-    entries.push(classic_entry());
     entries.push(dark_entry());
+    entries.push(classic_entry());
     entries.extend(discover_user_themes(user_dir));
     ThemeRegistry { entries }
 }
@@ -264,8 +264,8 @@ mod tests {
         let tmp = tempfile::tempdir().unwrap();
         let registry = build_registry(tmp.path());
         assert_eq!(registry.len(), BUNDLED_COUNT);
-        assert_eq!(registry.entries[0].id, "classic");
-        assert_eq!(registry.entries[1].id, "dark");
+        assert_eq!(registry.entries[0].id, "dark");
+        assert_eq!(registry.entries[1].id, "classic");
     }
 
     #[test]