Main nav current state highlight when viewing post

Hello,

I have a main navigation for my key pages and I have a current state set up in my CSS. So when you go to one of the main pages, the nav reflects this by highlighting.

Some of my main pages list thumbnails of specific posts. When you click on the post, you view that post – when viewing the post my navigation sets itself. I’d lie to have the nav current state remain while view a post.

So these are not sub pages but rather a post that I reached from a main page. Ideally I’m looking for a CSS tag like current-ancestor element but for posts and not pages.

Any ideas?
Tanks,
Rich