Inner Items in UWP Grid not stretching - xaml

Question

I am Having an issue with my items in this Grid not spanning the width of the screen. Sorry if my code is sloppy. A bit new at this.
Thanks in advance!
Not the full code - wasn't sure if you would need it.
<Grid x:Name="grid" Margin="0,0,0,54" VerticalAlignment="Bottom" Height="39" Style="{Binding HorizontalAlignment, ElementName=grid}" ScrollViewer.HorizontalScrollBarVisibility="Auto" >
<StackPanel Orientation="Horizontal" >
<Button Margin="0,12,0,-2" Height="32" Width="Auto" HorizontalContentAlignment="Stretch">
<Button.Content>
<Image Source="images/icon1.png" Margin="-9.667,-3,-9.667,-1"/>
</Button.Content>
</Button>
<Button Margin="0,12,0,-2" Height="32" Width="Auto" HorizontalContentAlignment="Stretch" >
<Button.Content>
<Image Source="images/icon2.png" Margin="-10,-3,-10,-1"/>
</Button.Content>
</Button>
<Border Background="#d1d3d4" x:Name="typeHeader11" Grid.Column="1" Margin="0,24,0,9" RenderTransformOrigin="0.5,0.5" Width="17" HorizontalAlignment="Stretch">
<Border.RenderTransform>
<CompositeTransform ScaleX="-1"/>
</Border.RenderTransform>
<Image Source="images/like.png"></Image>
</Border>
<Border Background="#d1d3d4" x:Name="typeHeader" Grid.Column="2" Margin="0,24,0,9" Width="67" HorizontalAlignment="Stretch">
<TextBlock Text="221" Width="20" Margin="0,7,0,10" FontSize="10.667" />
</Border>
<Border x:Name="typeHeader12" Grid.Column="1" Margin="0,24,0,9" RenderTransformOrigin="0.5,0.5" Width="17" HorizontalAlignment="Stretch">
<Border.RenderTransform>
<CompositeTransform ScaleX="-1"/>
</Border.RenderTransform>
<Image Source="images/dislike.png"></Image>
</Border>
<Border x:Name="typeHeader2" Grid.Column="2" Margin="0,24,0,9" Width="56" HorizontalAlignment="Stretch">
<TextBlock Text="221" Width="20" Margin="0,7,0,10" Foreground="#FFFDF3F3" FontSize="10.667" />
</Border>
<Border x:Name="typeHeader13" Grid.Column="1" Margin="0,24,0,9" RenderTransformOrigin="0.5,0.5" Width="17" HorizontalAlignment="Stretch">
<Border.RenderTransform>
<CompositeTransform ScaleX="-1"/>
</Border.RenderTransform>
<Image Source="images/comment.png"></Image>
</Border>
<Border Background="#d1d3d4" x:Name="typeHeader3" Grid.Column="2" Margin="0,24,0,9" Width="57" HorizontalAlignment="Stretch">
<TextBlock Text="221" Width="20" Margin="0,7,0,10" FontSize="10.667" />
</Border>
</StackPanel>
</Grid>

Answer 1

StackPanel does not stretch, use Grid and columns if you want to span items to the width of screen
<Grid x:Name="grid" ...>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/> // Auto adjust space
<ColumnDefinition Width="Auto"/> // Auto adjust space
<ColumnDefinition Width="*"/> // * = Stretch to fill
<ColumnDefinition Width="Auto"/> // Auto adjust space
</Grid.ColumnDefinitions>
<Button Grid.Column="0" ... />
<Button Grid.Column="1" ... />
<Button Grid.Column="2" ... /> // This will now expand as you resize window
<Button Grid.Column="3" ... />
</Grid>