Write valid web pages with XHTML and CSS

How to verify if a page is valid ?

To check HTML and XHTML, you can use the online validator at validator.w3.org.
They also have an online validator for CSS at jigsaw.w3.org.

Some XHTML / HTML5 hints

• Valid nested lists in XHTML
• How to do a valid <br clear="both"> in XHTML

Modern Web technic

• An AJAX example
• Using Webfonts

MathML

• List of commonly used Math symbols and their use in MathML

Special Chars and how to use them

• How to include special chars using HTML entities
• List of most common Math Unicode Entities
• Some special chars often used for electronics

Browser tests

• Does your browser support SVG? (Scaled vector graphics)
• Test of your browser supports MathML