Has anyone else experienced issues with the signin dialog on Safari? I think the root cause of the issue is that Safari does not respect the viewport metadata:
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
On smaller screens, users often need to scroll the dialog up after clicking into the username field and the soft keyboard is displayed. Many users first reaction is to pinch zoom as well. Here are a couple of screenshots of what users are experiencing.
Users who are using Chrome for iOS are not experiencing these issues.