Why can't I set the background color of a selected ListBoxItem in WPF?

Question

When a user clicks on an ListBoxItem, I want to it to be a bold larger font red background yellow

Everything works except the background. It seems that there is a st

Answer 1

Thanks Frances!! That did it for me, well somewhat. Here is my code that allows for the template to use the "StrColor" property for the selected and non-selected list items.