Extra themes are a pro feature

app/src/main/java/eu/faircode/email/ActivityBase.java

@@ -86,6 +86,11 @@ abstract class ActivityBase extends AppCompatActivity implements SharedPreferenc
             int uiMode = getResources().getConfiguration().uiMode;
             Log.i("UI mode=" + uiMode);
 
+            if (!this.getClass().equals(ActivitySetup.class) &&
+                    !ActivityBilling.isPro(this) &&
+                    (theme.contains("yellow") || theme.contains("red")))
+                theme = "blue_orange_light";
+
             switch (theme) {
                 case "light":
                 case "blue_orange_light":