<Grid x:Name="LayoutRoot" RenderTransformOrigin="0.5,0.5">
        <Viewbox Stretch="Uniform">
            <Button x:Name="butSelector" Width="250" Height="250" Style="{DynamicResource Button_Round_Style}" Background="{x:Null}" BorderBrush="{x:Null}" Foreground="{x:Null}">
                <Grid Width="250" Height="250">
                    <Grid x:Name="grdSymetryHost" Width="250" Height="250">
                        <Grid x:Name="grdLetter" Margin="0" Width="250" Height="250">
                            <Rectangle Fill="#FF424242" RadiusX="30" RadiusY="30" Width="250" Height="250"/>
                            <TextBlock  x:Name="txtLetter" 
                      FontFamily="{DynamicResource Font_Patient_Sans}"
                      FontSize="240" 
                      Text="T"
                      Foreground="{DynamicResource Background_Brush}" TextAlignment="Center" LineHeight="1" Margin="0,-15,0,0" VerticalAlignment="Center" FontWeight="Bold"/>
                        </Grid>
                    </Grid>
                </Grid>
            </Button>
        </Viewbox>
    </Grid>