I can't speak for device development, but the way in which I've always cheated this was to capture common resolutions, and watch for resize events.
Basically, I would build 320x240.css, 640x480.css, 800x600.css, etc., have an event listener polling for windowWidth, and change to the best stylesheet available. If you were, for example, at 799px width, you got the 640x480 display.
This was, of course, labor intensive, so you don't do this for everything. The last project I employed this on was done many years ago, and HAD TO look good at almost any resolution. This worked out well, except for images (which there were very very few of in this app), but that could be swapped out on resize as well, if you were really had to make it perfect.
Basically, I would build 320x240.css, 640x480.css, 800x600.css, etc., have an event listener polling for windowWidth, and change to the best stylesheet available. If you were, for example, at 799px width, you got the 640x480 display.
This was, of course, labor intensive, so you don't do this for everything. The last project I employed this on was done many years ago, and HAD TO look good at almost any resolution. This worked out well, except for images (which there were very very few of in this app), but that could be swapped out on resize as well, if you were really had to make it perfect.