When you are resizing a window, how to you tell how wide it is? I’m not good at guessing what’s 620px, for example. It is hard to choose which width should trigger new styles for media queries without a “ruler” to tell how wide the screen is at any given time. Do you have some kind of width add-on that tells you your viewport size as you are working?
But seeing the list above, I’d better check out some of that stuff too. Ha!