Fix react-error-overlay iframe overlay

[nattui]

Sometimes when working on a project, it creates this container around the entire app during hot reload. It happens during create-react-app: 4.x.x

Upon further inspection it looks like it is an which is rendered in the browswer as this:

<iframe style="position: fixed; top: 0px; left: 0px; width: 100%; height: 100%; border: none; z-index: 2147483647;"></iframe>

This solution uses CSS to make this particular iframe never a target of pointer events.

Fixes:

• https://stackoverflow.com/questions/70499543/create-react-app-creates-this-iframe-that-prevents-me-from-clicking-or-editing
• https://stackoverflow.com/questions/69051008/react-injecting-iframe-with-max-z-index-on-reload-after-changes-development

Closes #11773