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This page is intended as a "cheat sheet" only.   It is by no means exhaustive, and merely reflects our personal understanding of the technologies at the time we studied them.   We accept no responsibility for inaccuracies or outdated material.   Please refer to W3 Schools and the World Wide Web Consortium (W3C) for a full and current treatment of the technologies touched upon here.

Cascading Style Sheets (CSS)

This section defines just a few aspects of CSS. For a full treatment, we highly recommend Eric A. Meyer's CSS Web Site Design (New Jersey: Prentice Hall, 2008).

Properties

  • Describe aspects of an element's presentation
  • Examples: border-width, color, font-size

Attributes

  • Describe certain aspects of elements.
  • Examples: alt, class, height, id, src, width

Values

  • Every attribute must have a value.
  • Even if the value is empty, it must be present, surrounded by quotation marks (single or double): alt=""
  • A value is a descriptor defining an appearance, measurement, percentage, etc.   Ex: #333, x-large.

Declaration

  • A property-value pair: color: #333;
  • Declaration block: a set of declarations grouped together and surrounded by braces; e.g.
        {
            color: #333;
            border: 1px solid navy;
        }

Selector

  • An element to which declarations are applied: e.g., h1 {color: red;}
  • Descendent selector: a selector that is inside another element; e.g., #main h1 { }
  • Element ("simple") selector; e.g., p
  • ID selector; e.g., #masthead
    • html is the only element that cannot have an id attribut.
    • You can restrict which type of element / id pair should be selected; e.g., div#intro

Rule

  • The pairing of a selector and a declaration block: h1 {color: red}

Style Sheet

  • A collection of rules applied to a document
  • Can be embedded or external

Style Element

  • An embedded "container" to which CSS rules can be added
  • Form: <head>
                  <style type="text/css">
                      body {background-color: #999;}
                  </style>

MIME Types

  • MIME = Multipurpose Internet Mail Extensions
  • Describes a file's content
  • Examples:
    • text/css
    • text/javascript
    • image/gif

Uniform Resource Locator (URL)

Relative

  • Address is relative to the document in which it appears (e.g., href="../shell.css").
  • ../ means "up one level"

Absolute

  • Address is complete (e.g., href="http://www.notelinks.com/shell.css")
  • The "http://" is required.

XHTML

Elements

  • The structural pieces of a document.
  • Marked by start and end tags.
  • Replaced elements point to another resource that will replace the element when the page is rendered.
    Example: <img href="..." />
  • Non-replaced elements contain content. Ex: h1, h2, etc.

Attributes

  • Describe certain aspects of elements.
  • Examples: alt, class, height, id, src, width

Values

  • Every attribute must have a value.
  • Even if the value is empty, it must be present, surrounded by quotation marks (single or double): alt=""