all element inside container has 900px width, why #nav has 960px width?
remove wrong syntax from css file
use class css selector, making the css file neat and clean
eal fix of the issue for #nav div sticking out
again, use class for top level block for css selector
remove something unnecessary
remove non html5 supported tag
code convention for god sake
use css for background image, try to avoid using <img> tag as much as possible
add back gap on top of header, and add new gap at bottom after footer
remove something that doesn't effect anything
move style property from html tag to css style sheet
add "clear fix" kind of div to #nav container to solve all floating elements make the container holding no space