Button and eclipse

<Button Command="{Binding PlaceStoneCommand}" Width="30" Height="30" Cursor="Hand">
                                    <Button.Template>
                                        <ControlTemplate TargetType="{x:Type Button}">
                                            <Border x:Name="border" BorderThickness="1" BorderBrush="Black">
                                                <Ellipse Margin="0,2,0,0" Width="20" Height="20" Stretch="UniformToFill">
                                                    <Ellipse.Fill>
                                                        <SolidColorBrush Color="{Binding ColorCell.Value, Converter={StaticResource PlayerToColorTilesConvertor}}"/>
                                                    </Ellipse.Fill>
                                                </Ellipse>
                                            </Border>
                                            <ControlTemplate.Triggers>
                                                <Trigger Property="IsMouseOver" Value="True">
                                                    <Setter TargetName="border" Property="BorderBrush" Value="Red" />
                                                </Trigger>
                                            </ControlTemplate.Triggers>
                                        </ControlTemplate>
                                    </Button.Template>
                                </Button>