private void ButtonClose_Click(object sender, RoutedEventArgs e)
{
Storyboard storyboard = new Storyboard();
DoubleAnimation daWidth = new DoubleAnimation(SideMenu.ActualWidth, 0, new Duration(TimeSpan.FromSeconds(0.4)));
storyboard.Children.Add(daWidth);
Storyboard.SetTarget(daWidth, SideMenu);
Storyboard.SetTargetProperty(daWidth, new PropertyPath(WidthProperty));
SideMenu.BeginStoryboard(storyboard);
}