ColumnDefinition.Width=Auto

   
       

<Page x:Class="WebPageNavigation.Page1"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  WindowTitle="Page1"
  >
  <Grid>
    <StackPanel Grid.Column="0" Grid.Row="0" HorizontalAlignment="Left" Name="StackPanel1" 
                VerticalAlignment="Top">
        <TextBlock FontSize="18" HorizontalAlignment="Center" Margin="0,0,0,15">StackPanel1</TextBlock>

        <Button Margin="0,10,0,10">Button 1</Button>
        <Button Margin="0,10,0,10">Button 2</Button>
        <Button Margin="0,10,0,10">Button 3</Button>

        <TextBlock>ColumnDefinition.Width="Auto"</TextBlock>
        <TextBlock>StackPanel.HorizontalAlignment="Left"</TextBlock>
        <TextBlock>StackPanel.VerticalAlignment="Top"</TextBlock>
        <TextBlock>StackPanel.Orientation="Vertical"</TextBlock>
        <TextBlock>Button.Margin="0,10,0,10"</TextBlock>
    </StackPanel>
  </Grid>
</Page>