How do I set ListBox item font to bold? - Continued #2

Question

C# wpf --- This is a "continuation" of c-sharpcorner.com/forums/how-do-i-set-listbox-item-font-to-bold.

<ListBox x:Name="gLBx"
    Margin="5,0,5,0"
    Foreground="#FF0000"
    FontWeight="Bold"/>

This does not change the font to bold.

<ListBox x:Name="gLBx" 
    Margin="5,0,5,0" 
    Foreground="#FF0000">
    <ListBox.ItemContainerStyle>
        <Style TargetType="ListBoxItem">
            <Setter Property="FontWeight" Value="Bold"/>
        </Style>
    </ListBox.ItemContainerStyle>
</ListBox>

This, also, does not change the font to bold.