渐变色
<Border CornerRadius="8" BorderThickness="2" BorderBrush="#BF66FF">
<Border.Background>
<LinearGradientBrush StartPoint="1,1" EndPoint="0,0">
<LinearGradientBrush.GradientStops>
<GradientStop Offset="0.0" Color="#9E01AB"/>
<GradientStop Offset="0.5" Color="#4A0197"/>
</LinearGradientBrush.GradientStops>
</LinearGradientBrush>
</Border.Background>
</Border>
原文:https://www.cnblogs.com/microsoft-zh/p/15246480.html