How to add classes to the first active block of the slick slider and the last active block if you have 4 blocks visible?

Question

css

There is a slider with 4 visible blocks, I need the class to be added to the first active slide and the last one, when the slide is changed, the classes are recalculated, this is necessary to add styles to the first and last active slide, how many slides will be initially unknown, maybe 5 and 6 visible blocks. Therefore, this must be taken into account.

Answer 1