In chrome, Press the left feather touch button, and check if "Request Desktop Site" is unticked. Toggle and refresh to see if it makes any changes. I doubt this is going to work, because the site is configured to automatically adapt to the screen size. Can you check if you have any apps emulating your screen size to be something bigger, because that would explain the behaviour. Have you tried landscape/protrait modes?
On your desktop, try and resize the browser to a small width and see the size change.