Hi there.. im new in css, I want to make a custom layout for top border & menu 100% in width, but the other container is 980px in width.., how do i do that? here's my code..

/* layout */
#container {
width: 980px;
margin-left: auto;
margin-right: auto;
text-align: left;
border-top: 10px solid #CCC;
border-bottom: 39px solid #CCC;
padding-bottom: 5px;
}

somebody help me