Visual Studio/WPF > Error: CS0747 이니셜라이저 멤버 선언자가 잘못되었습니다. > 인수 지정 실수

Windows 7 Pro (32bit)
Microsoft Visual Studio 2017 Community

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
//
using System.Collections.ObjectModel;

namespace _170608_t1820_treeview
{
    /// <summary>
    /// MainWindow.xaml の相互作用ロジック
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }
    public class Category : ObservableCollection<Category>
    {
        public Category()
        {
        }
        public Category(string name)
        {
            Name = name;
        }
        public string Name { get; set; }
        public Category Children { get; set; }
    }
    public class OSAndBrowser
    {
        public Category Categories { get; set; }
        public OSAndBrowser()
        {
            Categories = new Category()
            {
                new Category("OS")
                {
                    Children = new Category("Windows")
                    {
                        Children = new Category
                        {
                            new Category("Windows 10"),
                            new Category("Windows 8.1"),
                        }
                    },
                    new Category("Mac OS X")
                }
            };
        }
    }
}

   public class OSAndBrowser
    {
        public Category Categories { get; set; }
        public OSAndBrowser()
        {
            Categories = new Category()
            {
                new Category("OS")
                {
                    Children = new Category
                    {
                        new Category("Windows")
                        {
                            Children = new Category
                            {
                                new Category("Windows 10"),
                                new Category("Windows 8.1"),
                            }
                        },
                        new Category("Mac OS X")
                    }
                }
            };
        }
    }