Custom _app.js imported from an external package errors when using global CSS

[ghost]

I have a custom _app used in numerous projects so I wanted to move it to an external package. All of my apps would look like this:

_app.js

import CustomApp from 'package';
export default CustomApp

I can't seem to get this working if I have global CSS inside of the CustomApp due to this error:

Global CSS cannot be imported from files other than your Custom <App>.

Has anyone been able to get around this? I found numerous related issues but not quite the same as this one. Thought I would ask here first.

[ghost]

My current solution is to import the global CSS separately into each app's _app.js like this:

_app.js

import CustomApp from 'package';

import 'custom.css';

export default CustomApp

I'd prefer to keep it all in CustomApp though :)