Make Windows Form look same across Desktop, Tablet and NoteBook screens using C#

Hi! I have form in C# windows application. I want use it application in desktop and notebook or tablet. But its size different. How I can define device desktop for universal device?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
namespace RKeeper
{
    public partial class User : Form
    {
        public static bool istxtLogActive = true;
 
        public User()
        {
            InitializeComponent();
            btnGroup();
        }
 
        private void User_Load(object sender, EventArgs e)
        {
            this.Size = Screen.PrimaryScreen.WorkingArea.Size;
        }
 
        private void btnClick(object sender, EventArgs e)
        {
            string number = (sender as Button).Text;
            if (istxtLogActive)
            {
                txtLog.Text += number;
            }
            else
            {
                txtPas.Text += number;
            }
        }
 
        private void TextBox_LostFocus(object sender, EventArgs e)
        {
            if ((sender as TextBox).Name == "txtLog")
            {
                istxtLogActive = true;
            }
            else
            {
                istxtLogActive = false;
            }
        }
 
        public void btnGroup()
        {
            int w = (int)this.ClientSize.Width; // ширина окна           
            int h = (int)this.ClientSize.Height; // высота окна
            //this.ClientSize = new System.Drawing.Size(w * h, h * w);
            txtLog.LostFocus += new EventHandler(TextBox_LostFocus);
            txtPas.LostFocus += new EventHandler(TextBox_LostFocus);
            btn1.BackColor = Color.Green;
            btn2.BackColor = Color.Green;
            btn3.BackColor = Color.Green;
            btn4.BackColor = Color.Green;
            btn5.BackColor = Color.Green;
            btn6.BackColor = Color.Green;
            btn7.BackColor = Color.Green;
            btn8.BackColor = Color.Green;
            btn9.BackColor = Color.Green;
            btn0.BackColor = Color.Green;
            btn10.BackColor = Color.Green;
            btn11.BackColor = Color.Green;
            btn12.BackColor = Color.Red;
            btn1.Click += new EventHandler(btnClick);
            btn2.Click += new EventHandler(btnClick);
            btn3.Click += new EventHandler(btnClick);
            btn4.Click += new EventHandler(btnClick);
            btn5.Click += new EventHandler(btnClick);
            btn6.Click += new EventHandler(btnClick);
            btn7.Click += new EventHandler(btnClick);
            btn8.Click += new EventHandler(btnClick);
            btn9.Click += new EventHandler(btnClick);
            btn0.Click += new EventHandler(btnClick);
            btn10.Click += new EventHandler(btnClick);
        }
 
        private void btn11_Click(object sender, EventArgs e)
        {
            string number = (sender as Button).Text;
            if (istxtLogActive)
            {
                txtLog.Text = "";
            }
            else
            {
                txtPas.Text = "";
            }
        }
 
        private void tmr_Tick(object sender, EventArgs e)
        {
            label2.Text = DateTime.Now.ToString("hh:mm:ss tt");
        }
 
        private void btn12_Click(object sender, EventArgs e)
        {
            if (txtLog.Text == "1" && txtPas.Text == "2")
            {
                mainForm mn = new mainForm();
                mn.ShowDialog();
            }
            else
            {
                MessageBox.Show("Логин ё рамз нодуруст аст!");
                txtLog.Focus();
            }
 
            txtLog.Text = "";
            txtPas.Text = "";
        }
 
        private void txtLog_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == 13)
                txtPas.Focus();
        }
 
        private void txtPas_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == 13)
                btn12.Focus();
        }       
    }
}