Add decimal button on NumPad for all platform

src/Calculator.Shared/Styles.xaml

@@ -480,6 +480,15 @@
 				Value="{StaticResource CalcOperatorCaptionSize}" />
 	</Style>
 
+	<Style x:Key="DecimalButtonStyle"
+		   BasedOn="{StaticResource OperatorButtonStyle}"
+		   TargetType="Controls:CalculatorButton">
+		<Setter Property="FontWeight"
+				Value="Bold" />
+		<Setter Property="FontSize"
+				Value="24" />
+	</Style>
+
 	<Style x:Key="SymbolOperatorButtonStyle"
 		   BasedOn="{StaticResource OperatorButtonStyle}"
 		   TargetType="Controls:CalculatorButton">

src/Calculator.Shared/Views/CalculatorProgrammerRadixOperators.xaml

@@ -424,7 +424,8 @@
 							 Grid.RowSpan="4"
 							 Grid.Column="2"
 							 Grid.ColumnSpan="3"
-											 ButtonStyle="{StaticResource NumericButtonStyle18}" />
+							 ButtonStyle="{StaticResource NumericButtonStyle18}"
+							 DecimalButtonStyle="{StaticResource DecimalButtonStyle}" />
 
 			<controls:CalculatorButton x:Name="aButton"
 									   x:Uid="aButton"

src/Calculator.Shared/Views/CalculatorScientificOperators.xaml

@@ -1034,6 +1034,7 @@
 						 Grid.Column="6"
 						 Grid.ColumnSpan="3"
 						 AutomationProperties.HeadingLevel="Level1"
-										 ButtonStyle="{StaticResource NumericButtonStyle24}" />
+						 ButtonStyle="{StaticResource NumericButtonStyle24}"
+						 DecimalButtonStyle="{StaticResource DecimalButtonStyle}" />
 	</Grid>
 </UserControl>

src/Calculator.Shared/Views/CalculatorStandardOperators.xaml

@@ -605,7 +605,8 @@
 						 Grid.Column="2"
 						 Grid.ColumnSpan="3"
 						 AutomationProperties.HeadingLevel="Level1"
-						 ButtonStyle="{StaticResource NumericButtonStyle24}" />
+						 ButtonStyle="{StaticResource NumericButtonStyle24}"
+						 DecimalButtonStyle="{StaticResource DecimalButtonStyle}" />
 
 		<controls:CalculatorButton x:Name="negateButton"
 								   x:Uid="negateButton"

src/Calculator.Shared/Views/NumberPad.xaml

@@ -118,10 +118,9 @@
         -->
 		<controls:CalculatorButton x:Name="decimalSeparatorButton"
 								   x:Uid="decimalSeparatorButton"
-								   Grid.Row="4"
+								   Grid.Row="3"
 								   Grid.Column="2"
-								   Style="{Binding ElementName=ControlRoot, Path=ButtonStyle}"
-								   Background="{ThemeResource AppBackgroundAltMediumLowBrush}"
+								   Style="{x:Bind Path=DecimalButtonStyle, Mode=OneWay}"
 								   AutomationProperties.AutomationId="decimalSeparatorButton"
 								   ButtonId="Decimal"
 								   IsEnabled="{Binding IsDecimalEnabled}" />

src/Calculator.Shared/Views/NumberPad.xaml.cs

@@ -22,6 +22,7 @@ namespace CalculatorApp
 {
 	public sealed partial class NumberPad : UserControl
 	{
+		#region ButtonStyle
 		public Style ButtonStyle
         {
             get { return (Style)GetValue(ButtonStyleProperty); }
@@ -30,7 +31,20 @@ namespace CalculatorApp
 
         // Using a DependencyProperty as the backing store for ButtonStyle.  This enables animation, styling, binding, etc...
         public static readonly DependencyProperty ButtonStyleProperty =
-            DependencyProperty.Register("ButtonStyle", typeof(Style), typeof(NumberPad), new PropertyMetadata(null));
+            DependencyProperty.Register(nameof(ButtonStyle), typeof(Style), typeof(NumberPad), new PropertyMetadata(null));
+		#endregion
+
+		#region DecimalButtonStyle
+		public Style DecimalButtonStyle
+		{
+			get { return (Style)GetValue(DecimalButtonStyleProperty); }
+			set { SetValue(DecimalButtonStyleProperty, value); }
+		}
+
+		public static readonly DependencyProperty DecimalButtonStyleProperty =
+			DependencyProperty.Register(nameof(DecimalButtonStyle), typeof(Style), typeof(NumberPad), new PropertyMetadata(null));
+		#endregion
+
 		private bool m_isErrorVisualState;
 
         public NumberPad()

src/Calculator.Shared/Views/UnitConverter.xaml

@@ -857,6 +857,7 @@
                              VerticalAlignment="Stretch"
                              AutomationProperties.HeadingLevel="Level1"
                              ButtonStyle="{StaticResource NumericButtonStyle24}"
+							 DecimalButtonStyle="{StaticResource DecimalButtonStyle}"
                              TabIndex="10"
                              TabNavigation="Local"/>
 			<controls:CalculatorButton x:Name="ConverterNegateButton"