In Webflow, when the target of a link (i.e. a section with an anchor) is in view, the link or link block gets the Current green class in the selector box. That’s when you style it.
Thank you very much @vincent, I got your point that those are anchor links linking to sections of the page, I have used ID for linking sidebar link blocks to the sections, so that when clicked it takes us to the specific section.
However, It will be great if you could provide me with a demo link or video or read-only link of how you have done this http://vertical-nav-menu.webflow.io/ so that it will be much easier for me to understand.
I figured out where I was doing wrong, I was linking to heading/h3 rather than the section/div. it’s working now. all I did is just gave IDs for all the div sections and linked the same with the anchor links/link blocks I had.
Now I can see the current state ( Green color) Thanks for your help!