Facebook: new IFrame canvas for page tab widths below 520 pixels?

Question

I am developing an application for Facebook pages, and as usual, I came across a strange error today. I know that the tab width should be 520px, but for some reason this does not happen on these new pages that use IFrame canvas instead of the old FBML.

Here is a screenshot documenting this error:

As you can see, the content is cropped (I used overflow: hidden to hide the scrollbars) at a total width of 504px. Any idea on how to solve it?

Answer 1

Just use Firebug to better verify this. This is really 520px:

Facebook, , reset . :

body {
    margin: 0;
    overflow: hidden;
    padding: 0;
}

overflow: hidden;.

Answer 2

. 520px.

script. , html body : .

Facebook Rulz.