We’re just dipping our toes into responsive web design and CSS3 media queries here at Stem Legal, but for those of you who’ve been working with it a bit longer, you may be interested in this recent article on A List Apart by Scott Kellum about how even something as simple as a pixel can mean different things on different devices:
… what is a pixel on high resolution devices today? Why does the 640px × 960px iPhone 4 claim to be 320px × 480px in the browser? The truth is that there are two different definitions of pixels: they can be the smallest unit a screen can support (a hardware pixel) or a pixel can be based on an optically consistent unit called a “reference pixel.”
The post offers some examples for using design-pixel-ratio, an alternative scale to check with CSS3. An interesting read for anyone working with media queries!