diff --git a/src/main/java/org/jabref/gui/preferences/AppearanceTabViewModel.java b/src/main/java/org/jabref/gui/preferences/AppearanceTabViewModel.java
index 8491f8ee8e8..6c55a346c11 100644
--- a/src/main/java/org/jabref/gui/preferences/AppearanceTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/AppearanceTabViewModel.java
@@ -63,7 +63,7 @@ public void setValues() {
             themeLightProperty.setValue(false);
             themeDarkProperty.setValue(true);
             themeCustomProperty.setValue(false);
-        } else if (ThemeLoader.MAIN_CSS.equals(currentTheme) || currentTheme.isBlank() || currentTheme.isEmpty()) {
+        } else if (ThemeLoader.MAIN_CSS.equals(currentTheme) || currentTheme.isBlank()) {
             themeLightProperty.setValue(true);
             themeDarkProperty.setValue(false);
             themeCustomProperty.setValue(false);
@@ -94,7 +94,7 @@ public void storeSettings() {
             restartWarnings.add(Localization.lang("Theme changed to dark theme."));
             preferences.put(JabRefPreferences.FX_THEME, ThemeLoader.DARK_CSS);
         } else if (themeCustomProperty.getValue() && !preferences.get(JabRefPreferences.FX_THEME).equals(ThemeLoader.getCustomCss())) {
-            restartWarnings.add(Localization.lang("Theme change to a custom theme."));
+            restartWarnings.add(Localization.lang("Theme changed to a custom theme."));
             preferences.put(JabRefPreferences.FX_THEME, preferences.getPathToCustomTheme());
         }
     }
diff --git a/src/main/java/org/jabref/gui/preferences/ExportThemeDialog.java b/src/main/java/org/jabref/gui/preferences/ExportThemeDialog.java
index f779334338f..38f8baddcd3 100644
--- a/src/main/java/org/jabref/gui/preferences/ExportThemeDialog.java
+++ b/src/main/java/org/jabref/gui/preferences/ExportThemeDialog.java
@@ -1,7 +1,5 @@
 package org.jabref.gui.preferences;
 
-import com.airhacks.afterburner.views.ViewLoader;
-
 import javafx.beans.property.SimpleStringProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
@@ -22,6 +20,7 @@
 import org.jabref.logic.util.StandardFileType;
 import org.jabref.preferences.JabRefPreferences;
 
+import com.airhacks.afterburner.views.ViewLoader;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -59,7 +58,7 @@ public void initialize() {
         ObservableList<Theme> data =
                 FXCollections.observableArrayList(new Theme("Light theme", ThemeLoader.MAIN_CSS), new Theme("Dark theme", ThemeLoader.DARK_CSS));
 
-        if (!(ThemeLoader.getCustomCss().isBlank() || ThemeLoader.getCustomCss().isEmpty())) {
+        if (!(ThemeLoader.getCustomCss().isBlank())) {
             data.add(new Theme("Custom theme", ThemeLoader.getCustomCss()));
         }
 
@@ -106,22 +105,4 @@ private void exportCSSFile(String theme) {
                          }
                      });
     }
-
-    public static class Theme {
-        private SimpleStringProperty name;
-        private SimpleStringProperty path;
-
-        public Theme(String name, String path) {
-            this.name = new SimpleStringProperty(name);
-            this.path = new SimpleStringProperty(path);
-        }
-
-        public String getName() {
-            return name.get();
-        }
-
-        public String getPath() {
-            return path.get();
-        }
-    }
 }
diff --git a/src/main/java/org/jabref/gui/preferences/Theme.java b/src/main/java/org/jabref/gui/preferences/Theme.java
new file mode 100644
index 00000000000..11b9d97f0a5
--- /dev/null
+++ b/src/main/java/org/jabref/gui/preferences/Theme.java
@@ -0,0 +1,21 @@
+package org.jabref.gui.preferences;
+
+import javafx.beans.property.SimpleStringProperty;
+
+public class Theme {
+    private SimpleStringProperty name;
+    private SimpleStringProperty path;
+
+    public Theme(String name, String path) {
+        this.name = new SimpleStringProperty(name);
+        this.path = new SimpleStringProperty(path);
+    }
+
+    public String getName() {
+        return name.get();
+    }
+
+    public String getPath() {
+        return path.get();
+    }
+}
diff --git a/src/main/java/org/jabref/gui/util/ThemeLoader.java b/src/main/java/org/jabref/gui/util/ThemeLoader.java
index 063fa9459e1..ad86a272dd7 100644
--- a/src/main/java/org/jabref/gui/util/ThemeLoader.java
+++ b/src/main/java/org/jabref/gui/util/ThemeLoader.java
@@ -39,7 +39,7 @@ public class ThemeLoader {
 
     public static final String MAIN_CSS = "Base.css";
     public static final String DARK_CSS = "Dark.css";
-    public static String CUSTOM_CSS = "";
+    private static String CUSTOM_CSS = "";
 
     private static final Logger LOGGER = LoggerFactory.getLogger(ThemeLoader.class);
     private final Optional<URL> additionalCssToLoad;
diff --git a/src/main/resources/l10n/JabRef_en.properties b/src/main/resources/l10n/JabRef_en.properties
index f24eb0b9adc..e9ad163957a 100644
--- a/src/main/resources/l10n/JabRef_en.properties
+++ b/src/main/resources/l10n/JabRef_en.properties
@@ -456,12 +456,6 @@ Importing=Importing
 
 Importing\ in\ unknown\ format=Importing in unknown format
 
-Import\ CSS=Import CSS
-
-Import\ custom\ CSS\ file=Import custom CSS file
-
-Theme\ change\ to\ a\ custom\ theme.=Theme change to a custom theme.
-
 Include\ subgroups\:\ When\ selected,\ view\ entries\ contained\ in\ this\ group\ or\ its\ subgroups=Include subgroups: When selected, view entries contained in this group or its subgroups
 
 Independent\ group\:\ When\ selected,\ view\ only\ this\ group's\ entries=Independent group: When selected, view only this group's entries
@@ -2126,14 +2120,13 @@ Field\ cannot\ be\ empty.\ Please\ enter\ a\ name.=Field cannot be empty. Please
 Shared\ database=Shared database
 Lookup=Lookup
 
-Import\ theme=Import theme
-
-Export\ theme=Export theme
-
 Export\ theme\ as\ CSS=Export theme as CSS
-
 Could\ not\ export\ theme=Could not export theme
-
 Path\ to\ theme=Path to theme
-
 Theme\ name=Theme name
+Theme\ changed\ to\ a\ custom\ theme.=Theme changed to a custom theme.
+Import\ theme=Import theme
+Export\ Theme=Export Theme
+
+Import\ CSS=Import CSS
+Import\ custom\ CSS\ file=Import custom CSS file