Hey Pira, Yes that's no problem. Nearly the whole set is usable for 320x180 screen resolutions. If you use 480x270 and 16x16grid, it's no problem at all.
if you check out screenshot 4 (the one with the blue background and 2 lists) that was made for a 320x180 resolution with 16x16 icons.
Since all interactive elements are delivered in 3 sizes and all menu bgs as 16x16 tile elements it should work out well for this, except maybe the decorated border in screenshot 3 might get a bit tight on a smaller resolution.
I also added resolutions this was intented for in the description. Sorry that there was no clearer information available.