I tested it with an iPhone 4gs with Safari, and an Android 4.2 with Chrome / Firefox / Opera and all 4 browsers showed the same result.
I think it has to do with some sort of filtering on the screen size.
I just tested it on my desktop with IE using the F12 emulation to emulate a Windows Phone running IE10 – windows phone edition, and it shows the same result.
Desktop snapshot, the way it should be displaying.
And this is what it looks like when accessing it from a mobile device, this particular picture is an emulated Windows Phone.