So if I wanted to design an iPhone Plus app icon I could start my project @2x and then scale down to @1.5x for Spotlight icon right? Always better to downscale than upscale for high detail especially in Sketch 3 right? BUT what is @2x for the iPhone Plus icon? Does that mean 180px times 2 = 360px? So I'd start designing at 360px? @2x = 360px?