The last Kmart on the U.S. mainland sits at the west end of a busy suburban Miami shopping center, quiet and largely ignored.All around it are thriving chain stores attracting steady streams of customers in sectors where the former box-store chain was once a major player: Marshalls, Hobby Lobby, PetSmart and Dollar Tree.But at this all-but-last outpost of a company once famed for its “Blue Light Specials,” only an occasional shopper pops in, mostly out of curiosity or nostalgia, then leaves after buying little or nothing.Related video above: The last full-size Kmart in the 50 United States also recently closed”I hadn’t seen Kmart in so long,” said Juan de la Madriz, who came to the shopping center on a recent weekday to buy dog food at PetSmart. The architect spotted the Kmart and wondered if he could find a gift for his newborn grandson. He exited 10 minutes later having …