Tab block – how to get rid of borders?

Hi,

I’ve been having difficulty getting the menu to filter content correctly (posts marked as News were still showing under “Review” when filtering using the menu, for example).

As a solution, I started looking at the tabbed news block, which is a potential solution, only to come across this:

See that silver border? I don’t want that.

My question then is:

a) How can I get rid of that border? I couldn’t find any options anywhere.

b) How can I use the header menu to allow users to filter content? I.E, they could click “reviews” to see all reviews, click “reviews – console” to see all console reviews, or click “reviews – console – ps3” to only see PS3 reviews (and the same for other categories, like News, Reviews, etc)