API Previewer - Auto scroll

As part of our developer centre refresh, we're tweaking the Xero API Previewer. The user can send an API call, and when a response is received, the field is automatically pushed to the top of the viewport. Hella nifty.

Ideally, this would only happen when the viewport is too small to fit both the call and response fields - on a large/portrait monitor the page would remain stationary when the response comes in.