wpf 滚动条样式

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:local="clr-namespace:RsVPN">

    <!-- ScrollViewer 滚动条 -->
    <Style x:Key="ScrollBarThumb"  TargetType="{x:Type Thumb}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Thumb}">
                    <Grid>
                        <!--滚动条颜色-->
                        <Border Background="#646465" CornerRadius="3"/>
                    </Grid>
                </Co