There are four main pseudo-elements in CSS: before/after/first-letter/first-line. In the before/after pseudo-element selector, there is a content attribute that can insert content into the page.
Insert plain text
content: "Inserted article", or content:none does not insert content
#html <h1 id="这是h">这是h1</h1> <h2 id="这是h">这是h2</h2> #css h1::after{ content:"h1后插入内容" } h2::after{ content:none }
Embedded text symbols
You can use the content attribute The open-quote attribute value and the close-quote attribute value add nested literal symbols such as brackets, single quotes, and double quotes on both sides of the string. open-quote is used to add the starting text symbol, and close-quote is used to add the ending text symbol. Modify the above css:
h1{ quotes:"(" ")"; /*利用元素的quotes属性指定文字符号*/ } h1::before{ content:open-quote; } h1::after{ content:close-quote; } h2{ quotes:"\"" "\""; /*添加双引号要转义*/ } h2::before{ content:open-quote; } h2::after{ content:close-quote; }
Insert picture
content attribute can also insert pictures directly before/after the element
#html <h3 id="这是h">这是h3</h3> #css h3::after{ content:url(图片路径) }
Insert attribute value of element
The content attribute can directly use attr to obtain the attributes of the element and insert it into the corresponding position.
#html <a href="http://www.php.cn">这是链接</a> #css a:after{ content:attr(href); }
Insert item number
Use the counter attribute of content to append consecutive numbers to multiple items.
#html <h1 id="大标题">大标题</h1> <p>文字</p> <h1 id="大标题">大标题</h1> <p>文字</p> <h1 id="大标题">大标题</h1> <p>文字</p> <h1 id="大标题">大标题</h1> <p>文字</p> #css h1:before{ content:counter(my)'.'; } h1{ counter-increment:my; }
Item number modification
The default inserted item number It is numerical, 1,2,3. . . Automatic increment, you can also add text and styles to the project number. Still use the above html, css modification as follows:
h1:before{ content:'第'counter(my)'章'; color:red; font-size:42px; } h1{ counter-increment:my; }
Specify number type
Use content (counter name, number type) format The syntax specifies the numbering type. The reference to the numbering type can be based on the list-style-type attribute value of ul. Using the above html, the css is modified as follows:
h1:before{ content:counter(my,upper-alpha); color:red; font-size:42px; } h1{ counter-increment:my; }
Number nesting
Large numbers are nested within medium numbers, and medium numbers are nested within small numbers.
#html <h1 id="大标题">大标题</h1> <p>文字1</p> <p>文字2</p> <p>文字3</p> <h1 id="大标题">大标题</h1> <p>文字1</p> <p>文字2</p> <p>文字3</p> <h1 id="大标题">大标题</h1> <p>文字1</p> <p>文字2</p> <p>文字3</p> #css h1::before{ content:counter(h)'.'; } h1{ counter-increment:h; } p::before{ content:counter(p)'.'; margin-left:40px; } p{ counter-increment:p; }
It can be found in the output of the example that the numbers of p are consecutive. If you renumber the three p's after each h1, you can use the counter-reset attribute to reset it. Modifying the css of the above h1:
h1{ counter-increment:h; counter-reset:p; }
can also achieve more complex nesting, such as three-level nesting. .
#html <h1 id="大标题">大标题</h1> <h2 id="中标题">中标题</h2> <h3 id="小标题">小标题</h3> <h3 id="小标题">小标题</h3> <h2 id="中标题">中标题</h2> <h3 id="小标题">小标题</h3> <h3 id="小标题">小标题</h3> <h1 id="大标题">大标题</h1> <h2 id="中标题">中标题</h2> <h3 id="小标题">小标题</h3> <h3 id="小标题">小标题</h3> <h2 id="中标题">中标题</h2> <h3 id="小标题">小标题</h3> <h3 id="小标题">小标题</h3> #css h1::before{ content:counter(h1)'.'; } h1{ counter-increment:h1; counter-reset:h2; } h2::before{ content:counter(h1) '-' counter(h2); } h2{ counter-increment:h2; counter-reset:h3; margin-left:40px; } h3::before{ content:counter(h1) '-' counter(h2) '-' counter(h3); } h3{ counter-increment:h3; margin-left:80px; }
The complete DEMO is given below
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>CSS content</title> <style> .string p:after { margin-left: -16px; background: #fff; content: "支持"; color: #f00; } .attr p:after { content: attr(title); } .url p:before { content: url(https://img.php.cn/upload/article/000/000/009/587d87ecca52d563.jpg); display: block; } .test ol { margin: 16px 0; padding: 0; list-style: none; } .counter1 li { counter-increment: testname; } .counter1 li:before { content: counter(testname)":"; color: #f00; font-family: georgia,serif,sans-serif; } .counter2 li { counter-increment: testname2; } .counter2 li:before { content: counter(testname2,lower-roman)":"; color: #f00; font-family: georgia,serif,sans-serif; } .counter3 ol ol { margin: 0 0 0 28px; } .counter3 li { padding: 2px 0; counter-increment: testname3; } .counter3 li:before { content: counter(testname3,float)":"; color: #f00; font-family: georgia,serif,sans-serif; } .counter3 li li { counter-increment: testname4; } .counter3 li li:before { content: counter(testname3,decimal)"."counter(testname4,decimal)":"; } .counter3 li li li { counter-increment: testname5; } .counter3 li li li:before { content: counter(testname3,decimal)"."counter(testname4,decimal)"."counter(testname5,decimal)":"; } </style> </head> <body> <ul> <li> <strong>string:</strong> <p>你的浏览器是否支持content属性:否</p> </li> <li> <strong>attr:</strong> <p title="如果你看到我则说明你目前使用的浏览器支持content属性"></p> </li> <li> <strong>url():</strong> <p>如果你看到图片则说明你目前使用的浏览器支持content属性</p> </li> <li> <strong>counter(name):</strong> <ol> <li>列表项</li> <li>列表项</li> <li>列表项</li> </ol> </li> <li> <strong>counter(name,list-style-type):</strong> <ol> <li>列表项</li> <li>列表项</li> <li>列表项</li> </ol> </li> <li> <strong>counter(name)拓展应用:</strong> <ol> <li>列表项 <ol> <li>列表项 <ol> <li>列表项</li> <li>列表项</li> </ol> </li> <li>列表项</li> </ol> </li> <li>列表项 <ol> <li>列表项</li> <li>列表项</li> </ol> </li> <li>列表项 <ol> <li>列表项</li> <li>列表项</li> </ol> </li> </ol> </li> </ul> </body> </html>

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