How do I use "position: fixed" for tippy popup?

[0xF5T9]

Adding "position: fixed" didn't make my popup position relate to the browser viewport but to the tippy wrapper instead. 

And when I used Developer Tools to remove the Tippy wrapper inline styles (transform), it worked.

Before:

After:

So I guess I must configure something to achieve this behavior but I can't figure how.

This link : https://atomiks.github.io/tippyjs/v6/all-props/#popperOptions
mentioned I can use "popperOptions" prop to take full control over the tippy's positioning.
I try to add "strategy: 'fixed'" but I don't see any changes.

What am I doing wrong? Thank you.