the container fits the width of the window. your divs inside will fill the container. when the width of the window changes the divs will auto fill the container accordingly.
This is exactly how I do all my sites and I’ve never had the issue your seeing now.
Give it a shot, play with the idea, and see what you come up with. Part of developing and learning how to fix issues is just trying to see what fixes odd problems. You can also come across ways to fix other issues you’ve had even if what your trying doesn’t fix the current issue.
Thats how i found a great way to get vertical alignment using jquery. My boss asked me to do it, and like most employees I said, "yeah…sure…no problem." I started fooling around with ideas and boom dynamic vertical alignment. :D