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.
Education Needed[
^]
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.