Rounded form Corners

hi

Use this code to round the edge corners of the form.
The code works, but when increasing the size of the form or decreasing the size of the form, problems occur with the code

[DllImport("Gdi32.dll", EntryPoint = "CreateRoundRectRgn")]  
        private static extern IntPtr CreateRoundRectRgn  
        (  
            int nLeftRect,     // x-coordinate of upper-left corner  
            int nTopRect,      // y-coordinate of upper-left corner  
            int nRightRect,    // x-coordinate of lower-right corner  
            int nBottomRect,   // y-coordinate of lower-right corner  
            int nWidthEllipse, // width of ellipse  
            int nHeightEllipse // height of ellipse  
        );  
  
        public Form1()  
        {  
            InitializeComponent();  
            this.FormBorderStyle = FormBorderStyle.None;  
            Region = System.Drawing.Region.FromHrgn(CreateRoundRectRgn(0, 0, Width, Height, 20, 20));  
        }