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12.4. Selectors

CSS provides limited abilities to select the elements to which a given rule applies. Many stylesheets only use element names and lists of element names separated by commas, as shown in Example 12-2. However, CSS provides some other basic selectors you can use, though they're by no means as powerful as the XPath syntax of XSLT.

12.4.4. Pseudoclass Selectors

Pseudoclass selectors match elements according to a condition not involving their name. There are seven of these. They are all separated from the element name by a colon. For example, the first-child pseudoclass matches the first child element of the named element. When applied to Example 12-1, this rule italicizes the first, and only the first, step element:

step:first-child {font-style: italic}

The link pseudoclass matches the named element if and only if that element is the source of an as yet unvisited link. For example, this rule makes all links in the document blue and underlined:

*:link {color: blue; text-decoration: underline}

The visited pseudoclass applies to all visited links of the specified type. For example, this rule marks all visited links as purple and underlined:

*:visited {color: purple; text-decoration: underline}

The active pseudoclass applies to all elements that the user is currently activating (for example, by clicking the mouse on). Exactly what it means to activate an element depends on the context, and indeed not all applications can activate elements. For example, this rule marks all active elements as red:

*:active {color: red}

The linking pseudoclasses are not yet well-supported for XML documents because most browsers don't recognize XLinks. So far, Mozilla and Netscape 6, the only browsers that recognize XLinks, are the only browsers that will apply these pseudoclasses to XML.

The hover pseudoclass applies to elements on which the cursor is currently positioned but which the user has not yet activated. For example, this rule marks all these elements as green and underlined:

*:hover {color: green; text-decoration: underline}

The focus pseudoclass applies to the element that currently has the focus. For example, this rule draws a one-pixel red border around the element with the focus, assuming there is such an element:

*:focus {border: 1px solid red }

Finally, the lang pseudoclass matches all elements in the specified language as determined by the xml:lang attribute. For example, this rule uses the David New Hebrew font for all elements written in Hebrew (more properly, all elements whose xml:lang attribute has the value he or any subtype thereof).

*:lang(he) {font-family: "David New Hebrew"}

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