Here is a list of free e-books on web design and development. You can either browse them online or download them.

1. Web Style Guide

“A style guide for the interface with real long-run value, showing us deep principles of design rather than simply fashion and technology.”
http://www.webstyleguide.com/index.html

2.Software Engineering for Internet Applications

Free pdf book about web application development. Topics covered: Basics, Planning, Software Structure, User Registration and Management, Content Management, Software Modularity, Discussion, Adding Mobile Users To Your Community, Voice (VoiceXML), Scaling Gracefully, Search, Planning Redux, Distributed Computing with HTTP, XML, SOAP, and WSDL, Metadata, User Activity Analysis and Writeup.
http://philip.greenspun.com/seia/introduction

3. How to Design a Web Site: A Beginners Guide

http://www.web-source.net/web_design_course.htm

It’s very important to learn the principal of Web Design before one should dig into the syntax and technique of html and css. One always need to get the big picture right first.