I'm building a test page just to learn the whole process from start to finish, rather than little bits of tutorials. I've hit a stop though, I can't seem to get the margin at the top of the page to go away. I'd like to be filled with my header color. This is HTML5 by the way.
I have nothing in my header as of now:
And this is the CSS:
I plan on making this work in everything but IE for now. I just want to get CSS down, and worry less about IE. Also, I can't figure out how to get it to span the whole page. I'd like the nav bar to go from edge to edge. Any help is appreciated.
I have nothing in my header as of now:

HTML:
<header></header>
Code:
header {
height: 110px;
width: 100%;
background-image: url(images/header.png);
background-image: -webkit-gradient(linear, left top, left bottom, from(rgb(43,62,253)), to(rgb(63,117,255)));
}