WebPlus Starter Edition: Stretch to Fit Page Width

Hi all,

I have a question about a banner image I'm using at the top of my page.

I stretched it to fit the width of the page in the editor, but when I preview it, it doesn't go all the way across.

What gives? How do I do this?

It's just bars of color (flag colors) so it can be stretched without screwing any visuals up, but it just doesn't seem to be doing it.

Don't tell me I can't do this in the Starter Edition either?!

Thanks!