extension method to know windows has light mode or not.

lightmode.cs

        /// <summary>
        ///     Determine whether it is a light theme
        /// </summary>
        /// <returns></returns>
        /// <exception cref="InvalidOperationException"></exception>
        public static bool IsLightTheme()
        {
            using (var personalizeKey =
                   Registry.CurrentUser.OpenSubKey(@"Software\Microsoft\Windows\CurrentVersion\Themes\Personalize",
                                                   false))
            {
                return (int) (personalizeKey?.GetValue("SystemUsesLightTheme", 0) ?? 0) == 1;
            }
        }