Often when a designer touts how small his carbon footprint is, that means the visual impact of his clothes will likely be puny, too. Not so with Yael Aflalo, the founder of Reformation, who uses surprising silhouettes—a peekaboo panel here, a slung low shoulder strap there, just the right slit up a long skirt—to keep his 20- and 30-something customers looking on-trend and flirty. On the ecological side: almost all his wares are manufactured in the United States, all from sustainable fabrics.