diff --git a/G-Earth/src/main/java/gearth/extensions/InternalExtensionFormBuilder.java b/G-Earth/src/main/java/gearth/extensions/InternalExtensionFormBuilder.java
index 5db129b..e7b65be 100644
--- a/G-Earth/src/main/java/gearth/extensions/InternalExtensionFormBuilder.java
+++ b/G-Earth/src/main/java/gearth/extensions/InternalExtensionFormBuilder.java
@@ -55,6 +55,7 @@ public class InternalExtensionFormBuilder<L extends InternalExtensionFormLaunche
             extensionForm.extension = internalExtension;
             extensionForm.primaryStage = stage;
 
+            extensionForm.fieldsInitialized.fireEvent();
             GEarthExtension gEarthExtension = new InternalExtensionBuilder(internalExtension);
             observer.onExtensionProduced(gEarthExtension);
 
diff --git a/G-Earth/src/main/java/gearth/extensions/ThemedExtensionFormCreator.java b/G-Earth/src/main/java/gearth/extensions/ThemedExtensionFormCreator.java
index 5941757..2dd1d62 100644
--- a/G-Earth/src/main/java/gearth/extensions/ThemedExtensionFormCreator.java
+++ b/G-Earth/src/main/java/gearth/extensions/ThemedExtensionFormCreator.java
@@ -27,13 +27,18 @@ public abstract class ThemedExtensionFormCreator extends ExtensionFormCreator {
         primaryStage.setResizable(false);
         primaryStage.sizeToScene();
 
-        DefaultTitleBarConfig config = new DefaultTitleBarConfig(primaryStage, ThemeFactory.getDefaultTheme()) {
+        Theme defaultTheme = ThemeFactory.getDefaultTheme();
+        DefaultTitleBarConfig config = new DefaultTitleBarConfig(primaryStage, defaultTheme) {
             @Override
             public boolean displayThemePicker() {
                 return false;
             }
         };
         TitleBarController.create(primaryStage, config);
+        Platform.runLater(() -> {
+            primaryStage.getScene().getRoot().getStyleClass().add(defaultTheme.title().replace(" ", "-").toLowerCase());
+            primaryStage.getScene().getRoot().getStyleClass().add(defaultTheme.isDark() ? "g-dark" : "g-light");
+        });
 
         ExtensionForm extensionForm = loader.getController();
         extensionForm.fieldsInitialized.addListener(() -> extensionForm.extension.observableHostInfo.addListener(hostInfo -> {
@@ -42,12 +47,18 @@ public abstract class ThemedExtensionFormCreator extends ExtensionFormCreator {
                 Theme theme = ThemeFactory.themeForTitle(themeTitle);
                 if (config.getCurrentTheme() != theme) {
                     String styleClassOld = config.getCurrentTheme().title().replace(" ", "-").toLowerCase();
+                    String lightClassOld = config.getCurrentTheme().isDark() ? "g-dark" : "g-light";
                     String styleClassNew = theme.title().replace(" ", "-").toLowerCase();
+                    String lightClassNew = theme.isDark() ? "g-dark" : "g-light";
                     config.setTheme(theme);
                     Parent currentRoot = primaryStage.getScene().getRoot();
                     Platform.runLater(() -> {
                         currentRoot.getStyleClass().remove(styleClassOld);
                         currentRoot.getStyleClass().add(styleClassNew);
+                        if (!lightClassOld.equals(lightClassNew)) {
+                            currentRoot.getStyleClass().remove(lightClassOld);
+                            currentRoot.getStyleClass().add(lightClassNew);
+                        }
                     });
                 }
             }
diff --git a/G-Earth/src/main/java/gearth/ui/themes/DarkTheme.java b/G-Earth/src/main/java/gearth/ui/themes/DarkTheme.java
index 25f90da..f7139cc 100644
--- a/G-Earth/src/main/java/gearth/ui/themes/DarkTheme.java
+++ b/G-Earth/src/main/java/gearth/ui/themes/DarkTheme.java
@@ -11,6 +11,11 @@ public class DarkTheme implements Theme {
         return "G-Earth_Dark";
     }
 
+    @Override
+    public boolean isDark() {
+        return true;
+    }
+
     @Override
     public boolean overridesLogo() {
         return false;
diff --git a/G-Earth/src/main/java/gearth/ui/themes/LightTheme.java b/G-Earth/src/main/java/gearth/ui/themes/LightTheme.java
index 6e131fe..f5738da 100644
--- a/G-Earth/src/main/java/gearth/ui/themes/LightTheme.java
+++ b/G-Earth/src/main/java/gearth/ui/themes/LightTheme.java
@@ -11,6 +11,11 @@ public class LightTheme implements Theme {
         return "G-Earth";
     }
 
+    @Override
+    public boolean isDark() {
+        return false;
+    }
+
     @Override
     public boolean overridesLogo() {
         return true;
diff --git a/G-Earth/src/main/java/gearth/ui/themes/TanjiTheme.java b/G-Earth/src/main/java/gearth/ui/themes/TanjiTheme.java
index abf3078..8d25128 100644
--- a/G-Earth/src/main/java/gearth/ui/themes/TanjiTheme.java
+++ b/G-Earth/src/main/java/gearth/ui/themes/TanjiTheme.java
@@ -11,6 +11,11 @@ public class TanjiTheme implements Theme {
         return "Tanji";
     }
 
+    @Override
+    public boolean isDark() {
+        return false;
+    }
+
     @Override
     public boolean overridesLogo() {
         return false;
diff --git a/G-Earth/src/main/java/gearth/ui/themes/Theme.java b/G-Earth/src/main/java/gearth/ui/themes/Theme.java
index ee50c28..73460d8 100644
--- a/G-Earth/src/main/java/gearth/ui/themes/Theme.java
+++ b/G-Earth/src/main/java/gearth/ui/themes/Theme.java
@@ -5,6 +5,7 @@ public interface Theme {
     String title();
     String internalName();
 
+    boolean isDark();
     boolean overridesLogo();
     boolean overridesTitle();