How to use a declarative approach? So that you don't have to call the JS class?

[korenevskiy]

How to use a declarative approach? So that you don't have to call the JS class?
Please write an example in the description of the declarative approach?
So that you can simply set the sidebar classes. Because we use CMS and adding extra code provokes very large overhead costs. Which default classes should I use to create a sticky sidebar?