Misc. notes related to "CSS : Missing Manual"

Recently, I read CSS : The Missing Manual and I got to say that I was pretty satisfied. The book walks through the basics of CSS with examples. The book isn't very deep but covers well the basics.

Misc notes (mostly for myself):

Valid & good HTML & CSS:

• Remember the basic "official things"
• Right doctype for the HTML
• Validate HTML (for example with W3C HTML validator)
• Validate also CSS (W3C CSS Validator)
• Other important things
• Do not mix HTML & styles (no fonts etc)
• HTML is for structure & semantics, CSS is for the layout etc
• Maintainability : CSS class names preferably for content, not for the layout/presentation, for example:
• use "alert" instead of "red-highlight"
• use "news" instead of "left-side-bar"

Misc CSS/HTML notes:

• Block-level vs inline boxes
• Block-level (div, p, ...) : break before and after element
• Inline elements (strong, a, ...) : no break

Position

• absolute : one can define the position him/herself
• relative to its absolutely positioned parent (tag with absolute, relative or fixed positioning)
• in other words : positioned with respect to its containing block
• absolute positioned element is removed from the HTML flow, the space is freed
• relative : relative to elements "right place" at the HTML flow
• fixed : fixed position at the window
• static (the default) : element's box is generated as normal