I'm writing a UWP app and have a page with a full-page grid inside a scrollviewer with two even-width outer columns and two even-width inner columns. The right side of the page is a mirror of the left, and everything is aligned to the similar column on the opposite side. However, when I run my app and decrease the width, after a certain point only the third column shrinks. Before that point, all the columns adjust correctly. I don't have any width or minwidth properties set. If I set a fixed width on my grid, the columns resize to be even. I've tried changing which columns my elements are aligned to on various elements, removing the ScrollViewer, and double- and triple-checking for any min-widths being set anywhere.
<ScrollViewer HorizontalScrollMode="Auto" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto">
<Grid MinWidth="800" Background="{ThemeResource SystemControlBackgroundAccentBrush}" ManipulationMode="All">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="69*"/>
<ColumnDefinition Width="76*"/>
<ColumnDefinition Width="76*"/>
<ColumnDefinition Width="69*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="27*"/>
<RowDefinition Height="62*"/>
<RowDefinition Height="27*"/>
<RowDefinition Height="399*"/>
<RowDefinition Height="340*"/>
<RowDefinition Height="105*"/>
</Grid.RowDefinitions>
<Viewbox Margin="100,27,89.667,0" Grid.RowSpan="3" Height="63" VerticalAlignment="Top" Stretch="Uniform">
<RichTextBlock Foreground="White">
<Paragraph>
<Run Text="Home" FontSize="48" FontWeight="Bold" FontStretch="Normal"/>
</Paragraph>
</RichTextBlock>
</Viewbox>
<Viewbox Margin="90,27,100,0" Grid.RowSpan="3" Grid.Column="3" Height="63" VerticalAlignment="Top">
<RichTextBlock Foreground="White">
<Paragraph>
<Run Text="Away" FontSize="48" FontWeight="Bold"/>
</Paragraph>
</RichTextBlock>
</Viewbox>
<Rectangle Fill="White" Margin="0,0,-1,0" Stroke="#FF252525" Grid.RowSpan="6" HorizontalAlignment="Right" Width="2" Grid.Column="1"/>
<Button x:Name="HomeGoalBtn" Margin="320,0,0.667,0.667" Grid.Row="3" Click="button_Click" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Grid.ColumnSpan="2">
<RichTextBlock IsTextSelectionEnabled="False">
<Paragraph>
<Run Text="Goal" FontSize="48" Foreground="White" />
</Paragraph>
</RichTextBlock>
</Button>
<Button x:Name="AwayGoalBtn" HorizontalAlignment="Stretch" Margin="0.333,0,320,0.667" Grid.Row="3" VerticalAlignment="Stretch" Click="button_Click" Grid.ColumnSpan="2" Grid.Column="2">
<RichTextBlock IsTextSelectionEnabled="False">
<Paragraph>
<Run Text="Goal" FontSize="48" Foreground="White" />
</Paragraph>
</RichTextBlock>
</Button>
<Button x:Name="AwayShotBtn" Content="Button" HorizontalAlignment="Stretch" Margin="0.333,24.333,25,15" Grid.Row="4" VerticalAlignment="Stretch" Grid.Column="2"/>
<Button x:Name="AwayPenaltyBtn" Content="Button" HorizontalAlignment="Stretch" Margin="30,104.333,112,15" Grid.Row="4" VerticalAlignment="Stretch" Grid.Column="3"/>
<RichTextBlock Margin="10,10,0,0.667" Grid.Row="3" HorizontalAlignment="Left" Width="310">
<Paragraph TextAlignment="Center">
<Run Text="{x:Bind ViewModel.HomeScore, Mode=OneWay}" FontSize="200"/>
</Paragraph>
</RichTextBlock>
<RichTextBlock Margin="0,0,0,0.667" Grid.Row="3" Grid.Column="3" HorizontalAlignment="Right" Width="320">
<Paragraph TextAlignment="Center">
<Run Text="{x:Bind ViewModel.AwayScore, Mode=OneWay}" FontSize="200"/>
</Paragraph>
</RichTextBlock>
<Button x:Name="HomeShotBtn" Content="Button" HorizontalAlignment="Stretch" Margin="30.333,24.667,0,14.333" Grid.Row="4" VerticalAlignment="Stretch" Grid.Column="1" />
<Button x:Name="HomePenaltyBtn" Content="Button" HorizontalAlignment="Stretch" Margin="102,104.333,24.667,15" Grid.Row="4" VerticalAlignment="Stretch"/>
<Button x:Name="MenuBtn" Content="Button" Grid.Column="1" HorizontalAlignment="Left" Margin="30.333,20.167,0,8" Grid.Row="5" VerticalAlignment="Stretch" Width="250" Click="button3_Click"/>
</Grid>
</ScrollViewer>
This is how my page looks in the designer: