Responsive Web Design is all the craze at the moment. Watching websites cascade into different layouts as you resize the browser can even be mesmerising.
But there’s one facet of RWD that still remains a (properly) unsolved problem. Responsive Images.
Download the source files (twentytwelve child theme).
If you simply use CSS’s max-width: 100%; attribute, mobile sites will still be downloading full size images. That’s an issue, because if your desktop site has images 920px wide, the mobile version will still be downloading this massive image, making loading time slow.