ListView not stretching to fit content WPF XAML - wpf

Question

Hey Everyone I am trying to figure out why my content will not stretch horizontally to fit my ListView items. I have HorizontalContentAlignment set to stretch, I used almost this exact layout on a second page and the content stretches on the second page. So not exactly sure what is going on and why the content won't stretch.
Here is a picture of what I am talking about
here is the code
<Border>
<Border.Background>
<ImageBrush ImageSource="/Backgrounds/BlueWaveBackground.jpg"/>
</Border.Background>
<Grid>
<ScrollViewer VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" HorizontalAlignment="Center" >
<StackPanel VerticalAlignment="Center" HorizontalAlignment="Center" TextBlock.TextAlignment="Center">
<Border CornerRadius="10"
Background="{StaticResource ForegroundLightBrush}"
Padding="15 10 15 15"
Width="700"
Margin="50 50 50 0">
<StackPanel>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto"/>
<ColumnDefinition/>
<ColumnDefinition Width="auto"/>
<ColumnDefinition />
</Grid.ColumnDefinitions>
<!--First Last Username-->
<StackPanel Grid.Column="0" HorizontalAlignment="Center">
<TextBlock Text="First Name:" Margin="0 10 10 0" />
<TextBlock Text="Last Name:" Margin="0 14 10 0" />
<TextBlock Text="Username:" Margin="0 16 10 0"/>
</StackPanel>
<StackPanel Grid.Column="1" Orientation="Vertical" >
<TextBox Grid.Row="0" Text="{Binding SelectedUser.FirstName}"/>
<TextBox Text="{Binding SelectedUser.LastName}"/>
<TextBox Text="{Binding SelectedUser.UserName}"/>
</StackPanel>
<!--Email and EmployeeType-->
<StackPanel Grid.Column="2" HorizontalAlignment="Center">
<TextBlock Text="Email:" Margin="95 10 10 0" />
<TextBlock Text="Employee Type:" Margin="10 14 10 0" />
</StackPanel>
<StackPanel Grid.Column="3" Orientation="Vertical" >
<TextBox Grid.Row="0" Text="{Binding SelectedUser.Email}"/>
<TextBox Text="{Binding SelectedUser.EmployeeType}"/>
</StackPanel>
</Grid>
<StackPanel Orientation="Horizontal">
<Button Content="Add New User" Margin="15"/>
<Button Content="Update User" Margin="15"/>
<Button Content="Delete User" Margin="15"/>
<Button Content="Clear User Info" Margin="15"/>
</StackPanel>
<!--Data grid-->
<ListView ItemsSource="{Binding Users}"
SelectedItem="{Binding SelectedUser}"
Margin="0,20,0,0"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch"
HorizontalContentAlignment="Stretch"
MaxHeight="150"
x:Name="List">
<ListView.View>
<GridView AllowsColumnReorder="True" ColumnHeaderToolTip="Users">
<GridViewColumn Header="First Name" Width="Auto" DisplayMemberBinding="{Binding FirstName}"/>
<GridViewColumn Header="Last Name" Width="Auto" DisplayMemberBinding="{Binding LastName}"/>
<GridViewColumn Header="Email" Width="Auto" DisplayMemberBinding="{Binding Email}"/>
<GridViewColumn Header="UserName" Width="Auto" DisplayMemberBinding="{Binding UserName}"/>
<GridViewColumn Header="Employee Type" Width="Auto" DisplayMemberBinding="{Binding EmployeeType}"/>
</GridView>
</ListView.View>
</ListView>
</StackPanel>
</Border>
</StackPanel>
</ScrollViewer>
</Grid>
</Border>
Thanks for any suggestions!

Answer 1

I found the solution. I had to set my border width to auto.
<Border CornerRadius="10"
Background="{StaticResource ForegroundLightBrush}"
Padding="15 10 15 15"
Width="auto"
Margin="50 50 50 0">
<StackPanel>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto"/>