Like the Christmas Spectacular, “The Hard Nut” is retro-inspired. It takes place in the 1970s, with a comic-book look based on the off-kilter perspective of Charles Burns, the D.C.-born creator of such teen-horror graphic novels as “Black Hole” and “Blood Club.” The decor for the Stahlbaums’ Christmas party includes a white aluminum tree, a deluxe television console and the prominent positioning of a cocktail cart. The characters are superbly detailed, and masculinity and femininity are easily transferable. Mrs. Stahlbaum, portrayed with gallant faded grandeur by John Heginbotham, is desperate for her happy pills and the booze to wash them down. As Dr. Stahlbaum, Morris is benignly oblivious.