I never fully read this one but it's really good, probably required reading if you're serious about webdev
CSS: BEM/OOCSS/SMACSS methodologies, they make you think critically about the structure of you styles. Harry Roberts does good writeups on maintainable css.
I second Don't Make Me Think and I also liked Eloquent Javascript (that zoo has a bunch of new exotic animals since, so I don't know if it's the best bet. It's a fun book though)
High Performance Websites and Even Faster Websites http://shop.oreilly.com/product/9780596529307.do http://shop.oreilly.com/product/9780596522315.do
These two on website performance are good, though they're a bit dated (pre http2 etc).
High Performance Browser Networking http://shop.oreilly.com/product/0636920028048.do
I never fully read this one but it's really good, probably required reading if you're serious about webdev
CSS: BEM/OOCSS/SMACSS methodologies, they make you think critically about the structure of you styles. Harry Roberts does good writeups on maintainable css.
I second Don't Make Me Think and I also liked Eloquent Javascript (that zoo has a bunch of new exotic animals since, so I don't know if it's the best bet. It's a fun book though)