What's the issue?

In Gmail, amp-lightbox uses position: fixed!important; and top: 0!important which attaches it to the top of <iframe id="amp-iframe">. If the user scrolls down on the email and then triggers the light-box, the light-box will display above the viewport.

How do we reproduce the issue?

1. Send yourself an AMP email where you have to scroll down to trigger an amp-lightbox.
2. Once triggered, scroll up to see that the lightbox is fixed to the top of the amp-iframe.

Which AMP version is affected?

AMP4Email