It was one of a series of lacy white confections that skewed younger than anything we’ve seen on an Oscar runway lately. And other things surprised, too. A chartreuse feather-stitched tank top and matching harem pant was perhaps too outré, but then you’d see de la Renta’s enthusiasm paying off, as in a crocheted silver thread sweater that exposed an inch or so of midriff over a metallic ball skirt.