How to break in size 300 KB from Html ( 1 MB) file and some tag are opens but not closed due to completed 300KB using C#

static void FileSplit(string ipath)
{
    // open input file
    using (FileStream fsi = File.OpenRead(ipath))
    {
        bool completed = false; // completed when all parts created
        int i = 0; // part index
        byte[] buff = new byte[1024]; // read/write buffer

        while (!completed)
        {
            // part file path
            string opath = string.Format("{0}_{1}", ipath, i++);
            // processed part size
            int partsize = 0;

            // open part file
            using (FileStream fso = File.Create(opath))
            {
                // requirement for max part size
                while (partsize < 300000)
                {
                    // read from input file
                    int n = fsi.Read(buff, 0, 1024);
                    if (n > 0)
                    {
                        partsize += n;
                        // write to part file
                        fso.Write(buff, 0, n);
                    }
                    completed = (n < 1024 || i > 10);
                    // break loop if completed
                    if (completed)
                        break;
                }
            }
        }
    }
} // end of file split