HTML & CSS
- W3C: List of valid DTDs
- A List Apart: Fixing your site with the right DOCTYPE
- WAI guidelines 7.2: HTML version information
- List of published formal grammars (as used by the W3C Validation Service
HTML / XHTML
- XHTML 1.0 Specifications
- HTML 4.01 Specifications
- W3C Technical Reports and Publications: Recently published recommendations
- Evolt: The XHTML Transition: It's not that difficult.
- WaSP asks the W3C: Which should we use, HTML or XHTML, and why?
- XHTML: Differences between Strict & Transitional.
- Common XHTML Validation Errors explained.
- Bulletproof XHTML by Evan Goer (September 2003).
- Cascading Style Sheets (CSS1) Level 1 Specification
- Cascading Style Sheets, level 2 (CSS2) Specification
- HTML 4.01 Specifications: Style Sheets
- WebReview.com's Style Sheet Reference Guide
- Web Design Group: Cascading Style Sheets (tutorials, references)
- Adding a touch of style, by Dave Raggett from the W3C
- WebReview: Style Sheet Reference Guide
- CSS Support Charts - browser support for the CSS1 and CSS2 specification.
- CSS Hacks and Filters - targetting browsers and hiding CSS.
- Integrated Web Design: CSS Beyond the Retrofit by Molly E. Holzschlag (February 2004) (introduction to the fundamentals of CSS)
- Cascading Style Sheets: Separating Content from Presentation, by Owen Briggs, Steve Champeon, Eric Costello and Matt Patterson. January 2002. Publisher: glasshaus.