I can't put an icon over a card without it disappearing behind the card or in the card and behind the other item in the card (ie image) same as using mobile banners - cant put them on the top most layer like a banner should be able to. Think if wanting to say its a best seller banner, it won't stay on the top layer. Possibly have a lock option but for layers? 'Lock at front' or 'Lock on this level' once you've got it where you want it
