Identify currently-open Node element

What I need

Hello I want to make currently opened node as much visible as possible in graph view (by adding animation to the css).

Therefore I need to somehow able to identify this currently opened node with css selector.

Thanks for any kind of advice

Additionally

Is there some reasonable way to find out id or class of elements from graph view ?

Things I have tried

find out what is the name of element by looking at .css files of some of themes
and also by looking into developer mode window.