protected override void OnPaint(PaintEventArgs e)
{
using (var gradientBrush = new LinearGradientBrush(
this.ClientRectangle, Color.FromArgb(255, 60, 60, 60), Color.Black, LinearGradientMode.Vertical))
{
e.Graphics.FillRectangle(gradientBrush, ClientRectangle);
}
}