"A free visual guide to CSS
Learn by example: cssreference.io is a free visual guide to CSS. It features the most popular properties, and explains them with illustrated and animated examples."
Hackpad.com/ is the best wiki ever
Easy to edit documents keep everyone on the same page. Authorship colors show you who wrote what. Easy sharing. Invite collaborators by name or email, or just share the URL.
Link at the speed of thought. Just type '@' and you're creating links or new pages. Changes are emailed to everyone. Email reply to update pages quickly.
'We like to see Downdetector as the weatherman for the digital world: we detect when technology fails. Just like the weather, service interruptions and outages can't be predicted, and just like a weatherman, we can tell you what is going on.'