Why is container for fixed layout stretching?

[DesignLady94]

I have set up my layout using Bootstrap's 940px fixed layout (i.e. div 
class="container"). However, both the nav bar and the page content are 
stretching when I re-size the browser horizontally. This causes a problem 
with not all the content scrolling under the fixed background image I am 
using for the nav bar. How would I be able to keep the navbar and content 
from stretching? My site is at debbierking.com/bootstrap.