<Window.Background>
    <!--镜像渐变-->
    <RadialGradientBrush Center="0.5,0" GradientOrigin="0.5,-0.5" RadiusX="0.7" RadiusY="1.2">
        <GradientStop Color="#ff61baff" Offset="0"/>
        <GradientStop Color="#ff29384e" Offset="1"/>
    </RadialGradientBrush>
</Window.Background>