How to place a menu at the entire top of the layout?

Hi,

I'm wondering how to place my menu so it fills the entire top of the layout. I don't want any padding between the layout border and the menu.

Here's an example of what I mean: http://chestofcolors.com/

Also: Is it possible to create a gradient effect on the menus? As of now they seem a bit dull at times.

Thanks in advance; can't get my head around this. I'm a css-newbie.