Image 100% width

The homepage has a parralax image.
On the Reservation page however the image at the top is as wide as the screen. This is not a parralax but scrolls with page. How is this done? When I put a 100% width image in a module position it is as wide as the template and not as wide as my screen.

Thnx

Could you please post an url to your site - to a sample page where the change should be made?

My website is is still local.
What I mean is the image at the top :

http://demo.gavick.com/joomla25/steakho ... eservation

Thnx

Without an access to a live site I can;t help much. Perhaps you could post it live somewhere?