Menu bar fixed width with browser resize

I have a wordpress site with a navbar that seems to collapse upon itself when the browser is resized and/or viewed in a mobile device.

What can I do to make the header and navbar maintain the same width even when the browser is resized

site: http://131studios.com/wp

You could do something like this:

.header-full-width {min-width: 990px;}

Thanks. I did that and I also had to adjust some float settings but it worked. Thanks for your help