Hi,
We have take a closer look at your website and we find what causing the website is not responsive.
You have changed main container class and all classes are tied together for perfect responsiveness.
I recommend not changing any container classes.
You have change class="content-wrapper" into the class="container_13" due content-wrapper class is tied to all subclasses you should change it back to original.
Best way to achieve your required styling to add class next to the content-wrapper.
Here is example:
<div class="content-wrapper grey-background">
Then you add css style to the class grey-background.
.grey-background {background-color: #CCC;}
See if this solve your problem.
Danijel
