Currently I am using SharePoint 2013's Promoted Links to create Windows-8-like-tiles I was wondering if there was some CSS that could be done so that these tiles could have borders around the images instead of me editing the photos so that they have a border.
For example:
Now how would I make it so that these would have a black border around the rim of the tiles so that the white image background wouldn't blend in with the white background of the page?