Csharp 调整窗口大小时如何保持 StackPanel 启动

我希望当我最小化窗口时，StackPanel保持在它的位置上(保持在顶部，不要向下)，同时最小化窗口.

100

问题(GIF格式)

GIF Of The Problem

XAML代码

<Grid Padding="25">
    <NavigationView PaneDisplayMode="Top">
        <NavigationView.MenuItems>
            <NavigationViewItem Content="Test" IsSelected="False" Icon="PreviewLink" />
        </NavigationView.MenuItems>

        <Viewbox StretchDirection="Both" Stretch="Uniform" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Height="1111">
            <StackPanel Width="1400" Height="1000" Margin="85, 0, 0, 150">

                <Border CornerRadius="25" Background="#1D1D1D" Height="180" Width="300" Margin="-1099, 50, 10, 10">

                    <Canvas Background="#1D1D1D" Width="250" Height="200" HorizontalAlignment="Left">
                        <TextBlock FontSize="40" Padding="0, 35, 300, 0" Margin="115, 35, 0, 0" Text="Test"
                                   Foreground="#1D1D1D"
                                    />
                    </Canvas>
                </Border>

                <Border CornerRadius="25" Background="#1D1D1D" Height="180" Width="300" Margin="-420, -190, 10, 10">


                    <Canvas Opacity="50" Background="#1D1D1D" Width="250" Height="200" HorizontalAlignment="Left">
                        <TextBlock FontSize="40" Padding="0, 35, 300, 0" Margin="115, 35, 0, 0" Text="Test"
                                   Foreground="#1D1D1D"
                                    />
                    </Canvas>
                </Border>


                <Border CornerRadius="25" Background="#1D1D1D" Height="180" Width="300" Margin="260, -190, 10, 10">

                    <Canvas Background="#1D1D1D" Width="250" Height="200" HorizontalAlignment="Left">
                        <TextBlock FontSize="40" Padding="0, 35, 300, 0" Margin="115, 35, 0, 0" Text="Test"
                                   Foreground="#1D1D1D"
                                    />
                    </Canvas>
                </Border>


                <Border CornerRadius="25" Background="#1D1D1D" Height="180" Width="300" Margin="940, -190, 10, 10">

                    <Canvas Background="#1D1D1D" Width="250" Height="200" HorizontalAlignment="Left">

                        <TextBlock FontSize="35" Padding="0, 35, 300, 0" Margin="60, 35, 0, 0" Text="Test"
                                   Foreground="#1D1D1D"
                                    />
                    </Canvas>
                </Border>
            </StackPanel>
        </Viewbox>

    </NavigationView>

</Grid>