Also, Doug Crockford’s YUI Theater videos are very useful indeed (and come packed with Crockford attitude).
Complete, amazingly well kept site on all variances between browsers + lots on all main ID issues:
CSS-wise, the definitive guide is good for the technical side of how CSS works:
http://oreilly.com/catalog/9781565926226, but the reality of how to use it is better described by sites built around IE hacks:
And how to process png24s:
Note that all the above should now be looked at with performance in mind these days. Check YUI’s work:
And the Steve Souder book: