Current behavior:

I'm trying to run emotion 11 in a browser extension content script. The trouble is if that content script then runs in a page that is already running an emotion 11 app, then the app styles break. After a chat with @Andarist on the emotion-slack, he suggested I open an issue here and that this is probably the culprit:

To reproduce:

1. Build and install a browser extension that uses emotion 11 in a content script (I've made a test extension here: https://github.com/craigsketchley/emotion-11-extension).
2. Visit a page that uses emotion 11 in production mode (I've made a test app here: https://github.com/craigsketchley/emotion-11-app).
3. Watch styles break as soon as the content script loads.

Expected behavior:

Loading a second bundle which includes emotion 11 shouldn't break the styles of the existing emotion 11 app already running in the page.

Environment information:

In the app and extension:

• react version: 16.13.1
• @emotion/cache version: 11.0.0-next.13
• @emotion/react version: 11.0.0-next.13
• @emotion/styled version: 11.0.0-next.13