using System;

​

public class Program

{

    public static void Main()

    {

        DateTime timeUtc = DateTime.Parse("2019-03-31T21:24:15.183+0000").ToUniversalTime();

        TimeZoneInfo cstZone = TimeZoneInfo.FindSystemTimeZoneById("GMT Standard Time");

        DateTime cstTime = TimeZoneInfo.ConvertTimeFromUtc(timeUtc, cstZone);

        Console.WriteLine("The date and time are {0} {1}.", cstTime, cstZone.IsDaylightSavingTime(cstTime) ? cstZone.DaylightName : cstZone.StandardName);

    }

}