I notice on viper alley that they have like a forum with sub categories.
I created a high level category and checked it as "does not contain ads" then placed a sub category which "does contain ads".
On viper alley the top header stays red across the entire top with the sub categories under it. On mine just the left column darkens but the Ads and Last post is still on the right of it, it doesn't completely go across.
See example of viper alley...
If mine were red like this one, it is only red in that first column, it doesn't extend across the table into Ad and Last Post.