WPF LiveChart如何去除分片图序列的白色边框

<Window x:Class="LiveChartsDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:lvc="clr-namespace:LiveCharts.Wpf;assembly=LiveCharts.Wpf"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <lvc:PieChart>
            <lvc:PieSeries Values="{Binding Values}">
                <lvc:PieSeries.DataLabels>
                    <lvc:DataLabels Background="Transparent" Stroke="Transparent" StrokeThickness="0"/>
                </lvc:PieSeries.DataLabels>
            </lvc:PieSeries>
        </lvc:PieChart>
    </Grid>
</Window>

public class ChartPoint
{
    public string Label { get; set; }
    public double Value { get; set; }
}

public ObservableCollection<ChartPoint> Values { get; set; }