Fixed main theme

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

@@ -72,17 +72,20 @@ abstract class ActivityBase extends AppCompatActivity implements SharedPreferenc
         this.contacts = hasPermission(Manifest.permission.READ_CONTACTS);
 
         SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
-        String theme = prefs.getString("theme", null);
-        if ("system".equals(theme)) {
-            int uiMode = getResources().getConfiguration().uiMode;
-            Log.i("UI mode=" + uiMode);
-            if ((uiMode & Configuration.UI_MODE_NIGHT_YES) != 0)
+
+        if (!this.getClass().equals(ActivityMain.class)) {
+            String theme = prefs.getString("theme", null);
+            if ("system".equals(theme)) {
+                int uiMode = getResources().getConfiguration().uiMode;
+                Log.i("UI mode=" + uiMode);
+                if ((uiMode & Configuration.UI_MODE_NIGHT_YES) != 0)
+                    setTheme(R.style.AppThemeBlack);
+            }
+            if ("dark".equals(theme))
+                setTheme(R.style.AppThemeDark);
+            else if ("black".equals(theme))
                 setTheme(R.style.AppThemeBlack);
         }
-        if ("dark".equals(theme))
-            setTheme(R.style.AppThemeDark);
-        else if ("black".equals(theme))
-            setTheme(R.style.AppThemeBlack);
 
         prefs.registerOnSharedPreferenceChangeListener(this);