As Troester said, this is a J! template issue. You have a "wrapper" div, of class 'content_wrap_noright', which is set to a fixed width of 708px.
Our list is correctly being restricted to that width, because all our content is inside that wrapper.
The only reason the map you point uses the full page width is because it's a Google map image, and you've specified 900px as the fixed width of that map in the viz settings. And because a Google map is a single, non-breakable entity, it overflows that wrapper size of 708px.
The only way to solve this one is to find whatever it is in your J! template which is setting that 708px fixed content width using the 'content_wrap_noright' class, and up it to whatever you want.
-- hugh