This site, test.wordpress.com, disallows iframes. Here’s what preview looks like in production.
The workaround is to hit the open in new window arrow box. This opens preview in a new tab/window. This forks flow, which is especially cumbersome on touch devices.
Note that preview on the iPhone 6+ is beneath the toolbar, obscuring the controls. Also, Preview exhibits scroll bleed.
Here is preview with 3291.
There is some funkiness here, perhaps theme specific, in the tablet preview mode. The hamburger menu pushes down content and it doesn’t close.
This screen also exhibits scroll bleed.
My mobile testing setup is a mess right now, so I can’t test local changes on iPhone 6+. Instead, I’ll take this opportunity to plug xip.io compat. 🙂