> min-width which is not supported in all browsers
There's a very simple workaround. Reference a transparent, one pixel image and specify the desired minimum width.
At that resolution, you'd be somewhat insane to maximize your browser window. You should be using software that divides your screen into regions.
In OSX, the layering nature of windows to make drag-n-drop more usable sometimes becomes counter-productive.
There are times when I find I just want to focus on a single item and block everything else out, which forces me to either maximize Safari, or close down all my applications.
I don't care for Spaces too much right now, it's kind of buggy with Photoshop/Illustrator.
If you haven't already, you might want to give Think a try. It runs on OS X and might be exactly what you're looking for.
I'm a fan of the multi-monitor model. Two 20" LCDs are often cheaper than one 40" (not the same area, I know) and can be much more useful. My typical setups are:
screen one: rotated vertical with code
screen two: horizontal with command line and the app splitting horizontal real estate.
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screen one: full-sized game
screen two: web browser and IM client
So for individuals like myself, who run at 1920x1200, legibility is a significant issue unless I manually resize my browser window which is about as much of a pain in the ass as scrolling horizontally.
Sadly, there is no perfect solution when designing for the web. Horses for courses.