The code for the awesome category list you can see in the aside here.

It will:

• display all your categories with a post counter (using Bootstrap’s badge class)
• highlight when you’re on the matching category page
• be installed in 3 minutes !

Bootstrap navbar can have an “active” element highlighted which ease navigation. In Octostrap3 it is possible to control which menu is selected on each page or post.

As you can see on this page, it is possible to have a different theme for a given page or post (this one is the mighty flatty) !