Hide floating Portal button for logged in users

Hey all! I like the floating Portal button in the bottom right as a CTA for new visitors, but I want to hide it for anyone logged in (free or paid).

Not sure how to handle this. I know handlebars can identify logged in users with @members, but the line of code I need to add is CSS. Also the Portal code isn’t directly editable as it is Ghost code and not in any of the theme file. Any ideas?

Running Ghost 5.0 on Ghost Pro. Using Dashi theme.

I tried adding this to my header.hbs file because I assumed the header loads on every page, but obviously it didn’t work:

{{#if @member}}
    .gh-portal-triggerbtn-wrapper {display:none !important;}

Did you ever find a solution to your issue?
I am looking at something similar where is just want that button gone from the mobile version

Thank you