how can i make this header 100% wide?

I want to make this header 100% wide. I tried this on jsfiddle, but there's still some more margin left on the left and right.

CSS:

#header {
   background: url("../img/top-bg.png") repeat-x scroll 0 0 #3D668F;
   height: 44px;
 }

HTML:

<div id="header"></div>

Fiddle: http://www.jsfiddle.net/VgfaA/

jsfiddle has thier header 100% wide, so thats an good example!!! I even tried to put width:100% but it still doesn't work

I have added

html, body { padding:0;margin:0; }

:) Nice site