Kinds of Tags

Not all CSS definitions can be applied to all HTML or XHTML tags. Whether a particular CSS property can be applied (or not) depends on the nature of the tag. For the most part, it's fairly obvious if the property can be applied.

For example, you wouldn't expect the text-indent property, which indents the first line of a paragraph, to apply to an inline tag such as <b>, and it can't be. If you do find you need some help in this area, see this book's companion Web site (webbedenvironments.com/css_dhtml_ajax) for a list of the properties that can be used with a particular kind of HTML or XHTML tag.

HTML and XHTML tags can generally be sorted into three categories:

• Block-level tags place a line break before and after the element. Table 1.2 lists the block-level tag selectors that CSS can use.

  Table 1.2. Selectors for Block-Level Tags

  SELECTOR	HTML USE
  blockquote	Quote style
  br	Line break
  center	Center text
  dd	Definition description
  div	Division
  dl	Definition list
  dt	Definition term
  h1-6	Heading levels 1-6
  li	List item
  object	Object embedding
  ol	Ordered list
  p	Paragraph
  pre	Preformatted text
  table	Table
  td	Table data
  th	Table head
  tr	Table row
  ul	Unordered list

  
  

• Inline tags have no line breaks associated with the element. Table 1.3 lists the inline-tag selectors that CSS can use.

  Table 1.3. Selectors for Inline Tags

  SELECTOR	HTML USE
  a	Anchored link
  b	Bold
  big	Bigger text
  cite	Short citation
  code	Code font
  dfn	Defined term
  em	Emphasis
  font	Font appearance
  i	Italic
  img	Image embedding
  span	Localized style formatting
  strike	Strikethrough
  strong	Strong emphasis
  sub	Subscript
  sup	Superscript
  tt	Teletype font
  u	Underlined text
  input	Form input object
  select	Form select input area
  textarea	Form text input area

  
  

Tips

• Some coders just slap the <p> tag into their code to start a new paragraph tag without its closing </p>. The closing tag must be included if you want to define paragraphs using CSS.

• Although the break tag (<br>) does not have a closing tag, you can add styles to it. However, remember that in XHTML, the break tag becomes <br /> (with a space between the br and the /) so that it is self-closing.