Change Background size of wpf toggle button

We have a normal toggle button deisgned with wpf using XAML. Our toggle switch

However we would like to achieve the following button design, where the background fills the circular switch: Desired toggle switch

Is this achivable without creating a custom button, and by somehow increasing the background size to have almost the same size as the circle switch in the middle.

The style of our designed toggle button:

<ToggleButton x:Name="btn_Rly_1" Content="0" Height="24.4" Margin="54.78,31.355,0,0" VerticalAlignment="Top" Width="56.107" Unchecked="un" Checked="btn_test_Checked" Background="#d7568d" HorizontalAlignment="Left" />

I have written a style for the ToggleButton and hope it can solve your problem.

<ToggleButton Content="14" IsChecked="False" Padding="2">
    <ToggleButton.Style>
        <Style TargetType="{x:Type ToggleButton}">
            <Setter Property="OverridesDefaultStyle" Value="True" />
            <Setter Property="FocusVisualStyle" Value="{x:Null}" />
            <Setter Property="Background" Value="LightGray" />
            <Setter Property="Width" Value="180" />
            <Setter Property="Height" Value="90" />
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type ToggleButton}">
                        <!-- Root Container -->
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition />
                                <RowDefinition />
                            </Grid.RowDefinitions>
                            <!-- Used to determine the value of Border.CornerRadius. -->
                            <Rectangle x:Name="PART_OuterRadius" Grid.Row="0" />
                            <Border Background="{TemplateBinding Background}"
                                    BorderBrush="{TemplateBinding BorderBrush}"
                                    BorderThickness="{TemplateBinding BorderThickness}"
                                    CornerRadius="{Binding Path=ActualHeight, ElementName=PART_OuterRadius}"
                                    Padding="{TemplateBinding Padding}"
                                    SnapsToDevicePixels="True"
                                    Grid.RowSpan="2">
                                <Grid>
                                    <Grid>
                                        <Grid.RowDefinitions>
                                            <RowDefinition />
                                            <RowDefinition />
                                        </Grid.RowDefinitions>
                                        <Rectangle x:Name="PART_InnerRadius" Grid.RowSpan="2" />
                                    </Grid>
                                    <Grid x:Name="PART_Button"
                                            Width="{Binding Path=ActualHeight, ElementName=PART_InnerRadius}"
                                            Height="{Binding Path=ActualHeight, ElementName=PART_InnerRadius}"
                                            HorizontalAlignment="Left">
                                        <Ellipse Fill="White" />
                                        <!-- Scale the content and limit its size within a circular area. -->
                                        <Viewbox>
                                            <ContentPresenter Margin="5" />
                                        </Viewbox>
                                    </Grid>
                                </Grid>
                            </Border>
                        </Grid>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="True">
                                <Setter Property="HorizontalAlignment" Value="Right" TargetName="PART_Button" />
                                <Setter Property="Background" Value="LimeGreen" />
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </ToggleButton.Style>
</ToggleButton>