User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0 Build ID: 20180920131237 Steps to reproduce: Go to www.gmail.com. View any message that is wider than a normal phone portrait view is able to handle (such as embedded wide pixel HTML content). Actual results: Even with the 'always enable zoom' feature enabled, the view can only be enlarged, but not shrunk to fit the wide message on the screen. Expected results: Should be able to zoom out to 50% size to view the content that is too wide to fit. In Opera for Android, it can at least scroll side ways to view the content to the right. The only way to view the content in the right is to flip the phone into landscape mode.

I can confirm the issue on all branches with Nokia 6 (Android 7.1.1) and OnePlus 5T (Android 8.1.0). If you can send us a logcat will be helpful for developers to understand easier the issue.

The viewport meta tag in the site is; <meta name="viewport" content="initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no, width=device-width"> And the body element has 'overflow-x:hidden', which means this is a dup of bug 1423013.