Originally Posted by Dr John

It's quite simple really, to see what has gone wrong. the div .top has a fixed width of 990px, so if the viewport is reduced, it sticks out the side.

It is also due to a common disease known as "being daft enough to design the layout with the design window set a full screen and then not checking the design in when it is resized", IE careless designer syndrome.

Possible solution? set a min-width on .container, and set .top to 100%