Appendix B: Changes from CSS1

CSS2 builds on [CSS1] and all valid CSS1 style sheets are valid CSS2 style sheets. The changes between the CSS1 specification and this specification fall into three groups: new functionality, updated descriptions of CSS1 functionality, and changes to CSS1.

2.1 New functionality

In addition to the functionality of CSS1, CSS2 supports:

• The concept of media types.
• Paged media
• Aural style sheets
• An extended font selection mechanism, including intelligent matching, synthesis, and downloadable fonts. Also, the concept of system fonts has been is introduced, and a new property, 'font-size-adjust', has been added.
• Tables, including new values on 'display' and 'vertical-align'.
• Relative and Absolute positioning, including fixed positioning.
• An extended selector mechanism, including child selectors, adjacent selectors and attribute selectors.
• Generated content and automatic numbering
• Text shadows, through the new
• 'text-shadow' property.
• A new anchor pseudo-class, :hover.
• System colors

2.2 Updated descriptions

The CSS1 specification was short and concise. This specification is much more voluminous and more readable. Much of the additional content describes new functionality, but the description of CSS1 features has also been extended. Except in a few cases described below, the rewritten descriptions do not indicate a change in syntax nor semantics.

2.3 Changes

• In CSS2 color values are clipped with regard to the device gamut, not with regard to the sRGB gamut as in CSS1.
• [strength of constraints based on writing direction]
• In CSS1, several properties (e.g. 'padding') had values referring to the width of the parent element. This was an error; the value should always refer to the width of a block-level element and this specification reflects this.
• Initial value of 'display' is 'inline', not 'block' as in CSS1.
• [the 'clear' property now only applies to block-level elements]