&what: Discover Unicode & HTML Character Entities : amp-what is a quick, interactive reference of 14,500 HTML character entities* and common Unicode characters, 8859-1 characters, quotation marks, punct...
Email Standards Project : The Email Standards Project is about working with email client developers and the design community to improve web standards support and accessibility ...
AlsacréationS : Alsacréations est une communauté dédiée à l'apprentissage des standards web (W3C, HTML, XHTML, CSS) ainsi qu'à l'accessibilité numérique
This site provides a collection of schemas that webmasters can use to markup HTML pages in ways recognized by major search providers, and that can also be used for structured data interoperability (e.g. in JSON).
Mobile HTML5 compatibility : HTML5 compatibility on mobile and tablet browsers with testing on real devices
The HTML5 Shiv : The HTML5 Shiv enables use of HTML5 sectioning elements in legacy Internet Explorer and provides basic HTML5 styling for Internet Explorer 6-9, Safari...
Onsen : Open source HTML5 hybrid app framework for PhoneGap & Cordova
Mobile-optimized HTML5, CSS and JavaScript with Web components
Responsive layout, Materi...
Docusaurus : Easy to Maintain Open Source Documentation Websites
TLDR pages : The TLDR pages are a community effort to simplify the beloved man pages with practical examples.