look at your styles.css
Body's width is set to 960px, while the Iframes width is set to only 800.
In each of your pages in the Iframe, you are loading the style, which is setting the content inside your Iframe larger than the Iframe itself. To make the scrollbars go away, you will need to set the width of the body inside of the iframe to less than 800. For example, 799px.
Alternatively, you can make the Iframe bigger, say 961px.
Good Luck! Tell me if it worked!