Full screen?

So I see all these flash templets around and all of them take up the entire screen. I like that look but when I try to do it there always seems to be a border where the SWF is on the page and I can see the back of the HTML page.

Is there something in actionScript that makes it do this? Or is it just something done in the html builder i.e. Dream Weaver. Thanks for any help you can give