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CSS 伪类 
CSS pseudo-classes are used to add special effects to some selectors.
CSS伪类可用来给一些选择器加上特殊效果。
实例
Hyperlink
This example demonstrates how to add different colors to a hyperlink in a document.
如何在文档内给超级连接加上不同的颜色
Hyperlink 2
This example demonstrates how to add other styles to hyperlinks.
如何给超级连接加上其他样式
:first-child (不能在IE中运行)
This example demonstrates the use of the :first-child pseudo-class.
演示 :first-child伪类的用法
:lang (不能在IE中运行)
This example demonstrates the use of the :lang pseudo-class.
演示 :lang伪类的使用方法
语法
The syntax of pseudo-classes:
伪类语法：
selector:pseudo-class {property: value}
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CSS classes can also be used with pseudo-classes:
类也可以使用伪类：
selector.class:pseudo-class {property: value}
|
Anchor Pseudo-classes
锚点伪类
A link that is active, visited, unvisited, or when you mouse over a link can all be displayed in different ways in a CSS-supporting browser:
当一个连接处于 活动，被访问，未访问或是当你鼠标移动到上面的时候都可以给它以不同的方式来表现，前提是浏览器支持CSS:
a:link {color: #FF0000} /* unvisited link */
a:visited {color: #00FF00} /* visited link */
a:hover {color: #FF00FF} /* mouse over link */
a:active {color: #0000FF} /* selected link */
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Note: a:hover MUST come after a:link and a:visited in the CSS definition in order to be effective!!
注意 a:hover 必须在a:link和 a:visited后出现，要有顺序才能正常显示效果！
Note: a:active MUST come after a:hover in the CSS definition in order to be effective!!
注意： CSS中a:active必须出现在a:hover定义后才能有效果！
Note: Pseudo-class names are not case-sensitive.
注意：伪类名称不区分大小写
Pseudo-classes and CSS Classes
伪类和CSS类
Pseudo-classes can be combined with CSS classes:
伪类可以与CSS类组合使用：
a.red:visited {color: #FF0000}
<a class="red" href="css_syntax.asp">CSS Syntax</a> |
If the link in the example above has been visited, it will be displayed in red.
如果上面的连接已经被访问过了，它就会显示为红色
CSS2 - The :first-child Pseudo-class
CSS2 中:first-child伪类
The :first-child pseudo-class matches a specified element that is the first child of another element.
:first-child伪类会匹配指定元素的子元素
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In this example, the selector matches any p element that is the first child of a div element, and indents the first paragraph inside a div element: div > p:first-child
{
text-indent:25px
}
This selector will match the first paragraph inside the div in the following HTML: <div> <p> First paragraph in div. This paragraph will be indented. </p> <p> Second paragraph in div. This paragraph will not be indented. </p> </div> but it will not match the paragraph in this HTML: <div> <h1>Header</h1> <p> The first paragraph inside the div. This paragraph will not be indented. </p> </div> |
|
In this example, the selector matches any em element that is the first child of a p element, and sets the font-weight to bold for the first em inside a p element: p:first-child em
{
font-weight:bold
}
For example, the em in the HTML below is the first child of the paragraph: <p>I am a <em>strong</em> man.</p> |
|
In this example, the selector matches any a element that is the first child of any element, and sets the text-decoration to none: a:first-child
{
text-decoration:none
}
For example, the first a in the HTML below is the first child of the paragraph and will not be underlined. But the second a in the paragraph is not the first child of the paragraph and will be underlined: <p> Visit <a href="http://www.w3schools.com">W3Schools</a> and learn CSS! Visit <a href="http://www.w3schools.com">W3Schools</a> and learn HTML! </p> |
CSS2 - The :lang Pseudo-class
CSS2 :lang伪类
The :lang pseudo-class allows you to define special rules for different languages. In the example below, the :lang class defines the type of quotation marks for q elements with a lang attribute with a value of "no":
:lang伪类允许定义不同语言的特殊规则。在下面的例子里:lang类通过一个lang属性值为"no"定义了q元素的引号类型:
<html>
<head>
<style type="text/css">
q:lang(no)
{
quotes: "~" "~"
}
</style>
</head>
<body> <p>Some text <q lang="no">A quote in a paragraph</q> Some text.</p> </body> </html> |
Pseudo-classes
伪类
浏览器支持: IE: Internet Explorer, F: Firefox, N: Netscape.
W3C: The number in the "W3C" column indicates in which CSS recommendation the property is defined (CSS1 or CSS2).
| 伪类 | 意图 | IE | F | N | W3C |
|---|---|---|---|---|---|
| :active | Adds special style to an activated element 指定活动元素的样式 |
4 | 1 | 8 | 1 |
| :focus | Adds special style to an element while the element has focus 为焦点元素加上指定样式 |
- | - | - | 2 |
| :hover | Adds special style to an element when you mouse over it 指定当你的鼠标移到元素上时所要表现的样式 |
4 | 1 | 7 | 1 |
| :link | Adds special style to an unvisited link 连接在未被访问前的样式 |
3 | 1 | 4 | 1 |
| :visited | Adds special style to a visited link 在其链接地址已被访问过时的样式 |
3 | 1 | 4 | 1 |
| :first-child | Adds special style to an element that is the first child of some other element 第一个子对象的样式 |
1 | 7 | 2 | |
| :lang | Allows the author to specify a language to use in a specified element 设置元素使用特殊语言的内容的样式。 |
1 | 8 | 2 |
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