Until recently, mobile ads were generally really bad. On one side, tiny and unreadable banners; on the other, invasive and obnoxious interrupts. But that is starting to change thanks to responsive design, which publishers have been moving to in droves in the second half of 2012 (including Mashable). Not only does responsive design optimize content for the screen you’re on, but it also optimizes advertising to serve the ideal sized unit. On a smartphone, that might mean a 300x250 ad. On a tablet or desktop, it’s likely a 970x90. And on an inbetween device like a 7” tablet or a plus-sized smartphone like the Galaxy Note, a 160x600.