CSS pseudo-class
CSS Pseudo-classes
CSS pseudo-classes are used to add some special effects to selectors.
Syntax
Pseudo class syntax:
CSS classes can also use pseudo-classes:
anchor pseudo-class
In browsers that support CSS, different states of the link can be displayed in different ways
Example
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<style>
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 */
</style>
</head>
<body>
<p><b><a href="http://www.php.cn/css/css-css_tutorial.html" target="_blank">这是一个链接</a></b></p>
<p><b>注意：</b> a:hover 必须在 a:link 和 a:visited 之后，需要严格按顺序才能看到效果。</p>
<p><b>注意：</b> a:active 必须在 a:hover 之后。</p>
</body>
</html>Run Example»
Click the "Run Example" button to view the online example
Note: In the CSS definition, a:hover must be placed between a:link and It is only valid after a:visited.
Note: In the CSS definition, a:active must be placed after a:hover to be valid.
Note: The names of pseudo-classes are not case-sensitive.
Pseudo classes and CSS classes
Pseudo classes can be used with CSS classes:
<a class="red" href="css-syntax.html">CSS Syntax</a>
If the link in the above example has been visited , it will appear in red.
CSS - :first - child pseudo-class
You can use the :first-child pseudo-class to select the first child element of an element
Note: In previous versions of IE8, <!DOCTYPE> must be declared so that :first-child can take effect.
Match the first <p> element
In the following example, the selector matches the <p> element that is the first child of any element:
Instance
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<style>
p:first-child
{
color:blue;
}
</style>
</head>
<body>
<p>This is some text.</p>
<p>This is some text.</p>
<p><b>注意:</b>对于 :first-child 工作于 IE8以及更早版本的浏览器, DOCTYPE必须已经声明.</p>
</body>
</html>Run Instance»
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Match the first <i> element among all <p> elements
In the following example, selects all <p> elements that match the first <i> element:
Instance
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<style>
p > i:first-child
{
color:blue;
}
</style>
</head>
<body>
<p>I am a <i>strong</i> man. I am a <i>strong</i> man.</p>
<p>I am a <i>strong</i> man. I am a <i>strong</i> man.</p>
<p><b>注意:</b> 当 :first-child 作用于 IE8以及更早版本的浏览器, DOCTYPE必须已经定义.</p>
</body>
</html>Run instance»
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Matches all <i> elements that are the first child of a <p> element
In the following example, the selector matches all elements that are the first All <i> elements within the <p> element of the child element:
Example
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<style>
p:first-child i
{
color:blue;
}
</style>
</head>
<body>
<p>I am a <i>strong</i> man. I am a <i>strong</i> man.</p>
<p>I am a <i>strong</i> man. I am a <i>strong</i> man.</p>
<p><b>注意:</b> 当:first-child 作用于 IE8及更早版本的浏览器, DOCTYPE 必须已经定义.</p>
</body>
</html>Run instance»
Click the "Run instance" button to view the online instance
CSS - :lang pseudo-class
:lang Pseudo-classes give you the ability to define special rules for different languages
Note: IE8 must declare <!DOCTYPE> to support the ;lang pseudo-class.
In the following example, the :lang class defines the type of quotes for the q element with attribute value no:
Example
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<style>
q:lang(no)
{
quotes: "~" "~";
}
</style>
</head>
<body>
<p>Some text <q lang="no">A quote in a paragraph</q> Some text.</p>
<p>在这个例子中,:lang定义了q元素的值为lang =“no”</p>
<p><b>注意:</b> 仅当 !DOCTYPE已经声明时 IE8支持 :lang.</p>
</body>
</html>Run instance»
Click the "Run instance" button to view online instances
More instances
Example: Add different styles to hyperlinks
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<style>
a.one:link {color:#ff0000;}
a.one:visited {color:#0000ff;}
a.one:hover {color:#ffcc00;}
a.two:link {color:#ff0000;}
a.two:visited {color:#0000ff;}
a.two:hover {font-size:150%;}
a.three:link {color:#ff0000;}
a.three:visited {color:#0000ff;}
a.three:hover {background:#66ff66;}
a.four:link {color:#ff0000;}
a.four:visited {color:#0000ff;}
a.four:hover {font-family:monospace;}
a.five:link {color:#ff0000;text-decoration:none;}
a.five:visited {color:#0000ff;text-decoration:none;}
a.five:hover {text-decoration:underline;}
</style>
</head>
<body>
<p>将鼠标移至链接上改变样式.</p>
<p><b><a class="one" href="http://www.php.cn/css/css-css_tutorial.html" target="_blank">This link changes color</a></b></p>
<p><b><a class="two" href="http://www.php.cn/css/css-css_tutorial.html" target="_blank">This link changes font-size</a></b></p>
<p><b><a class="three" href="http://www.php.cn/css/css-css_tutorial.html" target="_blank">This link changes background-color</a></b></p>
<p><b><a class="four" href="http://www.php.cn/css/css-css_tutorial.html" target="_blank">This link changes font-family</a></b></p>
<p><b><a class="five" href="http://www.php.cn/css/css-css_tutorial.html" target="_blank">This link changes text-decoration</a></b></p>
</body>
</html>Run Example»
Click the "Run Example" button to view the online example
This example demonstrates how to add additional styles to hyperlinks.
Instance: use: focus
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<style>
input:focus
{
background-color:yellow;
}
</style>
</head>
<body>
<form action="" method="get">
用户名: <input type="text" name="fname" /><br>
密 码: <input type="text" name="lname" /><br>
<input type="submit" value="Submit" />
</form>
<p><b>注意:</b>仅当 !DOCTYPE已经声明时 IE8支持 :focus.</p>
</body>
</html>Run instance»
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This example demonstrates how to use the :focus pseudo-class.
All CSS pseudo-classes/elements
| Selectors | Example | Example description |
|---|---|---|
| :checked | input:checked | Select all selected form elements |
| :disabled | input:disabled | Select all disabled form elements |
| :empty | p:empty | Select all p elements that have no child elements |
| :enabled | input:enabled | Select all enabled form elements |
| :first-of-type | p:first-of-type | Select each parent element that is the first p child element of the p element |
| :in-range | input:in-range | Select values within the specified range of elements |
| :invalid | input:invalid | Select all invalid elements |
| :last-child | p:last-child | Select the last child element of all p elements |
| :last-of-type | p:last-of-type | Select each p element that is the last p element of its parent element |
| :not(selector) | :not(p) | Select all elements except p |
| :nth-child(n) | p:nth-child(2) | Select the second child element of all p elements |
| :nth-last-child(n) | p:nth-last-child(2) | Select all p elements The second to last child element |
| :nth-last-of-type(n) | p:nth-last-of-type (2) | Select the second to last child element of p for all p elements |
| :nth-of-type(n) | p:nth-of-type(2) | Select all p elements whose second child element is p |
| : only-of-type | p:only-of-type | Select all elements with only one child element being p |
| :only-child | p:only-child | Select all p elements that have only one child element |
| :optional | input :optional | Select element attributes without "required" |
| :out-of-range | input:out-of-range | Select element attributes with values outside the specified range |
| :read-only | input:read-only | Select read-only attributes Element attributes |
| :read-write | input:read-write | Select element attributes that do not have read-only attributes |
| :required | input:required | Select the element attribute specified by the "required" attribute |
| :root | root | Select the root element of the document |
| :target | #news:target | Select the current active #news element (the click URL contains the name of the anchor) |
| :valid | input:valid | Select All properties with valid values |
| :link | a:link | Select all unvisited links |
| :visited | a:visited | Select all visited links |
| :active | a:active | Select the active link |
| :hover | a:hover | The state of placing the mouse on the link |
| :focus | input:focus | Select elements that have focus after input |
| ##:first-letter | p:first-letterSelect each The first letter of a<p> element | |
| :first-line | p:first-lineSelects the first row of each <p> element | |
| :first-child | p:first-childThe selector matches the <]p> element that is the first child element of any element | |
| p:before | Insert content before each <p> element | |
| :after | p:after | Insert content after each <p> element |
| ##:lang(language) | p:lang(it)Select a starting value for the lang attribute of the <p> element |
