Social networking and career profiles/portfolios for software and web developers and designers. Automatically aggregates content from open-source project hosts, other social networks, e-learning and learn-to-program sites, app stores, etc.
A free (libre), open-source (MIT license) HTML5 template built for responsive design. Skeleton's 12-column grid uses CSS media queries to automatically adjust page layout for the size of a viewer's screen or browser window.
The official CSS page at the W3 Consortium.
The "Learn & Use" page is crammed full of links to tutorials, articles, and events. The majority of resources are in English, but there appear to be a decent number in other languages as well.
The Open Share icon conveys the act of sharing by visually representing one hand passing an object to another hand, as in "pass it on" or "sharing". The icon also represents an "eye", as in "look at this".