Do you want to view this page over HTTP or HTTPS?
Do you want to pass or fail the test?
Now select a referrer policy.
Finally, choose a location to move to.
This "image" will load from the second site and will use the referrer poilcy which as been set. Rather than return an image, it returns text describing the referrer it sees.
This stylesheet will also get passed the referrer.
The Mozilla docs have a very good reference for all of these: Referrer-Policy.