I am trying the Gantry 4.0 for the first time and am leaving the Responsive option selected in the admin to take advantage of this feature.
I want to create a header that spans the entire Top position. So I have created a version (a JPG) that is 1200px wide to take advantage of the new wider format.
Now, how do I get it to either resize the 1200px jpg to 960px and other sizes for different sized browsers? Or use CSS to call for another image that is already resized?