This is the hackiest media query ever, but it does (currently) work. I maybe wouldn’t recommend using this unless you plan to keep an eye on device specs every time they release a new device. AND then you’d have to re-submit all of your titles.
the dumbest thing about this media query is that the Fire doesn’t care what value is assigned to device-aspect-ratio. you could do 1024/800, 19/6,1/1, 50/50. You can’t however just give it a number (say, like 1.6).