No CSS when using in Theme Builder

Content in popup is without any styling when I use it in Theme Builder.
Example: https://test.pysznepierogi.pl/danie/testowy-produkt/

While it is working fine on regular pages.
Example on the same site: https://test.pysznepierogi.pl/testing-popups/

Any ideas?
I made custom CSS but it would be great if it could work properly 😉