With Elementor, “Height = Fit To Screen” does not work in mobile mode. I talked to Elementor Team and they told me that <!DOCTYPE> has been removed and it’s a theme issue.
I don’t know how it did get lost since I don’t edit files manually.
The doctype looks like it’s still there for me. If you’d like to make sure, you can re-install the theme. Best way to do that is to go to “Appearance > Editor” and change the theme version near to the top to one version prior to the current version.
This will prompt WordPress to tell you there’s an update available.