This is how grid works. And if you want to change this, then you need to modify theme files but we do not recommend this because after that you won't be able to do theme updates. However if you want to play with code then please look at http://pastie.org/9961938 but please notice that if you don't know how it works, you should contact with your website developer.
Comments
when in mobile. it does not stretch all the way to the sides. only the revolution slider does this.