在ScrollViewer wpf中更改ScrollBar的背景颜色

<Window.Resources>
    <Style x:Key="CustomScrollBarStyle" TargetType="{x:Type ScrollBar}">
        <Setter Property="Background" Value="LightGray"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ScrollBar}">
                    <Grid Background="{TemplateBinding Background}">
                        <Track x:Name="PART_Track" IsDirectionReversed="True">
                            <Track.DecreaseRepeatButton>
                                <RepeatButton Command="ScrollBar.LineUpCommand" Content="▲"/>
                            </Track.DecreaseRepeatButton>
                            <Track.IncreaseRepeatButton>
                                <RepeatButton Command="ScrollBar.LineDownCommand" Content="▼"/>
                            </Track.IncreaseRepeatButton>
                            <Track.Thumb>
                                <Thumb Background="DarkGray" Width="10"/>
                            </Track.Thumb>
                        </Track>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>

<ScrollViewer VerticalScrollBarStyle="{StaticResource CustomScrollBarStyle}" HorizontalScrollBarStyle="{StaticResource CustomScrollBarStyle}">
    <!-- 内容 -->
</ScrollViewer>