For showcase set in gallery layout
Including the sliding funcionality between the items so user can slide them, a caroules basically.
After click on more info, on the lightbox - copy section - adapt the lightbox at the screen, and expand it throught tap (as the scrolling is working behind on the items below the lightbox)
For UI, on the lightbox, round corner also on top and bringing the X over the lightbox. I think there is an additional padding between image and css box, and that might be beneficial add sama padding also left and right side of the lightbox.
I would add something for ancor the lightbox to the item on the showcase, as when you close the lightbox you might end up far from the orininal item.