Sub-Subcategories?

[Zeemah]

Oh, that is obtained through custom CSS. It hasn’t been publicly posted, but you could perhaps try contacting them to see if they’d be willing to post it. Otherwise, I guess the logic would go as far as setting an image based on whichever class is being used for the category div of the category you wish to put a header above, also adding some padding to the bottom of (in this case, ‘Cookbook’).