Using a css selector to select a specific entity

I need to create an alert box on a client’s account on outbound links for compliance reasons. Currently, there is one single promotion entity for which this alert box needs to apply. Is there a way that I can just select this one entity?

I.e., something like .promotions > #Promotion1 {}?

When I inspect element, I do see that there’s the following HTML field/data pair. I’m not sure how to use this in the JS though.