A site that I like to point people to is dontfeartheinternet.com. It has great videos to learn the basics.
There are lots of people that blog interesting stuff, but it's kinda hard to name just a few. Sooner or later you'll find them by Googling or on Twitter.
I'm not really into reading books and rather learn by just experimenting. Maybe tools like codepen.io or cssdeck.com let you play around and see the result instantly updated.
There are also some online learning services like codecademy.com or teamtreehouse.com that teaches more in an interactive way.