private static boolean getBooleanDirect(final String prefKey, final boolean defaultValue) {
        try {
            return sharedPrefs == null ? defaultValue : sharedPrefs.getBoolean(prefKey, defaultValue);
        } catch (ClassCastException cce) {
            return defaultValue;
        }
    }
Follow the global system setting for dark mode.
main/src/main/java/cgeo/geocaching/settings/Settings.java