css

References

• Lie, H. W. (1994). Cascading HTML style sheets: a proposal. World Wide Web Consortium (W3C).

• Lie, H. W., & Bos, B. (2005). The CSS saga. In Cascading style sheets: Designing for the web. Addison-Wesley Professional.

Purpose

• • CSS is used to define the look and formatting of content.

    • • HTML is used to define the semantics of the content, without look and formatting or "presentation"

History

• • Versions

Syntax

• • A style sheet is a list of rules

  • Each rule is a selector followed by a declaration block

    • • selectors

        • • determine which parts of the DOM tree are affected

          • DOM tree selector

            • • refers to all elements of same type, or

              • elements with a particular local tree structure

              • e.g. p {color:red;} makes all paragraphs red

          • class selector

            • • refers to all elements in a user defined class

              • e.g. .myclass {background:blue;} makes all elements in the "myclass" class have blue background

          • ID selector

            • • refers to all elements with a user defined ID

              • e.g. #myelt {color:yellow;} makes the element labeled "myelt" yellow

          • pseduo class selector

            • • refers to element characteristics outside of the DOM, often dynamic characteristics

              • e.g. hover, visited

          • these can often be combined

      • declaration blocks

        • • each block is a list of property : value pairs

          • separate pairs by semicolons

      • example properties

        • • color

          • background

Cascading and inheritance

• • Styles come from

    • • Browser defaults

      • User defined styles

      • Author defined styles, in

        • • external files

            • • This is how you can centralize your styles, applying the same style to all your documents

              • Use the link element in your