Removing the space around the edge of a posting

Hello, I am using the catch-box theme and like it very much. There is one thing I would like to do though and that is to find out how to remove the border around a post when using the page template with no sidebar please. i.e If I want to show a calendar on a page, I would like to view it so that it takes up the full page width and not have a shaded border around the outside. Much like the footer is the full width of the page with no border. All help gratefully received :) Thank you.