private void EasyR_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
 {
     VisibleRects();
     HardR.AnimateOpacity(1);
     NormalR.AnimateOpacity(1);
     EasyR.AnimateOpacity(0, Completed: (element) => element.Visibility = Visibility.Hidden);
     difficulty = Difficulty.Easy;
 }
 private void NormalB_Clicked(object sender, EventArgs e)
 {
     VisibleRects();
     HardR.AnimateOpacity(1);
     EasyR.AnimateOpacity(1);
     NormalR.Visibility = Visibility.Hidden;
     ShowInputAnimate();
     difficulty = Difficulty.Normal;
 }