You can't get legal ebooks on internet. If you want hard copy then buy it from amazon. There are alternatives for ebooks. What about articles? Codeproject has a section The HTML5 / CSS3 Zone
BTW here more than couple of ways to learn anything in Internet.
If you want to read things in offline then you can save the web page in your PC. For example every Codeproject article contains a button Print
to print the article(with out ad) & read that in offline always.