2. [Emotional Design: Why We Love (or Hate) Everyday Things](http://www.amazon.com/exec/obidos/tg/detail/-/0465051359/) by Don Norman
3. [The Elements of Typographic Style](http://www.amazon.com/Elements-Typographic-Style-Robert-Brin...) by Robert Bringhurst
4. [Grid Systems](http://www.amazon.com/Systems-Graphic-Systeme-Visuele-Gestal...) by Josef Muller-Brockmann
5. [Ordering Disorder: Grid Principles for Web Design](http://www.amazon.com/Ordering-Disorder-Principles-Design-Vo...) by Khoi Vinh
6. [Why Customers Really Buy: Uncovering the Emotional Triggers That Drive Sales](http://www.amazon.com/Why-Customers-Really-Buy-Uncovering/dp...) by Linda Goodman (I've had the pleasure of meeting her and overhearing her office conversation during my daily tasks at the office in Houston, where she worked for a spell. Incredibly sharp, and it is clear that her principles exposed in this book are thorough-going in her interactions with people. I think it would be important to apply her research to Lean methodologies, building Features only around Emotional Triggers. This is what we are aiming at, but I am making this connection right now, I believe, in saying this.)
7. [Contextual Design: Defining Customer-Centered Systems](http://www.amazon.com/Contextual-Design-Customer-Centered-In...) by Hugh Beyer, Karen Holtzblatt
Although, nothing beats Brockmann's Grid Systems book mentioned earlier.
Learn about Object-Oriented CSS.
- A short intro: http://www.slideshare.net/stubbornella/object-oriented-css
- Reference: http://oocss.org/
- Nettuts tutorial 
Learn About Grid Systems.
- Ordering Disorder: Grid Principles for Web Design 
Learn about new CSS languages
- Sass & Scss
- Less css
Learn Css 3
- New Css selectors
- New Css new attributes
- Media Queries
- Modernizr and how to degrade in old browsers
- Book: Stunning CSS3: A project-based guide to the latest in CSS
- Book: Hardboiled Web Design
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