Magical CSS3 selector_html/css_WEB-ITnose-HTML Tutorial-php.cn

Home

Web Front-end

HTML Tutorial

Magical CSS3 selector_html/css_WEB-ITnose

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 24, 2016 am 11:40 AM

I have been involved in the garden for many years, but I have never written a blog. If I want to write some basics, let’s start with the css3 selector.

Css3 selector

Let’s first talk about why we advocate the use of selectors.

Using selectors, you can directly bind styles to elements. It is clear at a glance which styles match which elements in the style sheet, and it is also easy to modify.
Reduce the amount of code in style sheets.

Attribute Selector

　1.[att*=val]Attribute Selector

Meaning: Representation If the attribute value of the element's attribute represented by att contains the character represented by val, then the element uses this style

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        [id*=demo]        {            width: 100px;            height: 100px;            background-color: #000099;        }    </style></head><body><div id="demo"></div></body></html>

　 2.[att^=val ] Attribute selector

Meaning: If the attribute value of the attribute represented by att of the element starts with a string represented by val, then the element uses this style.

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        [id^=demo]        {            width: 100px;            height: 100px;            background-color: #000099;            margin: 10px;        }    </style></head><body><div id="demo"></div><div id="demo1"></div></body></html>

　3.[att$=val]Attribute selector

Meaning: Indicates the attribute value of the attribute represented by att of the element Ending with a string represented by val, the element uses this style

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        [id$=o]        {            width: 100px;            height: 100px;            background-color: #000099;            margin: 10px;        }    </style></head><body><div id="demo"></div><div id="demooo"></div></body></html>

Structural pseudo-class selector

Pseudo-class selectors refer to defined selectors and cannot be named casually.

For example: a:link, a:visited, a:hover, a:active.

Pseudo element selectors refer to selectors that have been defined for elements.

first-line pseudo-element selector

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">       p:first-line       {           color: red;       }    </style></head><body>  <p>      hello world      <br/>      你好  </p></body></html>

2.first-letter pseudo-element Selector

 <!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">       p:first-letter       {           color: red;       }    </style></head><body>  <p>      hello world  </p>  <p> 你好</p></body></html>

<strong>befor伪元素选择器</strong>

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">       li:before       {           content: '*';       }    </style></head><body>   <ul>       <li>demo1</li>       <li>demo1</li>       <li>demo1</li>       <li>demo1</li>       <li>demo1</li>   </ul></body></html>

after pseudo-element selector

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">       li:after       {           content: '*';       }    </style></head><body>   <ul>       <li>demo1</li>       <li>demo1</li>       <li>demo1</li>       <li>demo1</li>       <li>demo1</li>   </ul></body></html>

　root selector

　The root selector binds styles to the root element of the page. When using: the background of root and body elements, the display effect is different according to different conditions

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">       :root       {           background-color: #003300;       }        body        {            background-color: yellow;        }    </style></head><body><p>你好</p></body></html>

　not selector

Exclude Substructural element under the structural element so that it does not use the element

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        body *:not(h1)        {            background-color: yellow;        }    </style></head><body><h1 id="大家好">大家好</h1><p>你好</p></body></html>

　 empty selector

Used when the element content is empty style.

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        td:empty        {            background-color: yellow;        }    </style></head><body><table border="1">    <tr>        <td width="100px">1</td>        <td width="100px">2</td>        <td width="100px"></td>    </tr></table></body></html>

　target selector

Use the target selector to style the target element in the page

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        :target        {            background-color:yellow;        }    </style></head><body><table border="1">   <a href="#text3">示例1</a>    <div id="text1">        <h1 id="你好">你好</h1>        <p>你好你好你好你好你好你好你好你好你好你好你好你好你好你好</p>    </div>    <div id="text2">        <h1 id="你好">你好</h1>        <p>你好你好你好你好你好你好你好你好你好你好你好你好你好你好</p>    </div>    <div id="text3">        <h1 id="你好">你好</h1>        <p>你好你好你好你好你好你好你好你好你好你好你好你好你好你好</p>    </div></table></body></html>

　 First-child, last-child selectors

Specify the style of the first and last child elements

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">       li:first-child       {           background-color: yellow;       }        li:last-child        {            background-color: #009999;        }    </style></head><body><table border="1">   <ul>       <li>1</li>       <li>2</li>       <li>3</li>       <li>1</li>   </ul></table></body></html>

　nth-child, nth-last-child selectors

Specify the style for a child element with a specified sequence number in the parent element.

You can also use Nth-child(even) to specify styles for even-numbered elements, and Nth-child(odd) to specify styles for odd-numbered elements.

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">       li:nth-child(2)       {           background-color: yellow;       }        li:nth-last-child(2)        {            background-color: #009999;        }    </style></head><body><table border="1">   <ul>       <li>1</li>       <li>2</li>       <li>3</li>       <li>1</li>   </ul></table></body></html>

　nth-of-type nth-last-of-type selector

These two selectors are to make up for the shortcomings of nth-child and nth-last-child selectors. These two choices The handler only specifies styles for elements of the same type.

UI element status selector

E:horver,E:active,E:focus selector

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        input[type="text"]:hover        {            background-color: yellow;        }        input[type="text"]:focus        {            background-color: green;        }        input[type="text"]:active        {            background-color: red;        }    </style></head><body><input type="text" name="name"></body></html>

　　E:enabled,E:disabled,E:read-only,E:read-write selector

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        input[type="text"]:disabled        {            background-color: green;        }        input[type="text"]:read-only        {            background-color:darkgrey;        }    </style></head><body><input type="text" disabled><br><input type="text" ><br><br><input type="text" readonly="readonly" ></body></html>

　 E: checked, E: default selector

E: checked specifies the style when the check box is selected

E: default specifies Default selection box style

E::selection selector

Specifies the style when the element is selected

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title></title>    <style type="text/css">        p::selection        {            background-color: goldenrod;        }    </style></head><body> <p>测试测试</p></body></html>

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

What is the purpose of HTML tags?Apr 28, 2025 am 12:02 AM

HTMLtagsareessentialforstructuringwebpages,enhancingaccessibility,SEO,andperformance.1)Theyareenclosedinanglebracketsandusedinpairstocreateahierarchicalstructure.2)SemantictagslikeandimproveuserexperienceandSEO.3)Creativetagslikeenabledynamicgraphics

What are self-closing tags? Give an example.Apr 27, 2025 am 12:04 AM

Self-closingtagsinHTMLandXMLaretagsthatclosethemselveswithoutneedingaseparateclosingtag,simplifyingmarkupstructureandenhancingcodingefficiency.1)TheyareessentialinXMLforelementswithoutcontent,ensuringwell-formeddocuments.2)InHTML5,usageisflexiblebutr

Beyond HTML: Essential Technologies for Web DevelopmentApr 26, 2025 am 12:04 AM

To build a website with powerful functions and good user experience, HTML alone is not enough. The following technology is also required: JavaScript gives web page dynamic and interactiveness, and real-time changes are achieved by operating DOM. CSS is responsible for the style and layout of the web page to improve aesthetics and user experience. Modern frameworks and libraries such as React, Vue.js and Angular improve development efficiency and code organization structure.

What are boolean attributes in HTML? Give some examples.Apr 25, 2025 am 12:01 AM

Boolean attributes are special attributes in HTML that are activated without a value. 1. The Boolean attribute controls the behavior of the element by whether it exists or not, such as disabled disable the input box. 2.Their working principle is to change element behavior according to the existence of attributes when the browser parses. 3. The basic usage is to directly add attributes, and the advanced usage can be dynamically controlled through JavaScript. 4. Common mistakes are mistakenly thinking that values need to be set, and the correct writing method should be concise. 5. The best practice is to keep the code concise and use Boolean properties reasonably to optimize web page performance and user experience.

How can you validate your HTML code?Apr 24, 2025 am 12:04 AM

HTML code can be cleaner with online validators, integrated tools and automated processes. 1) Use W3CMarkupValidationService to verify HTML code online. 2) Install and configure HTMLHint extension in VisualStudioCode for real-time verification. 3) Use HTMLTidy to automatically verify and clean HTML files in the construction process.

HTML vs. CSS and JavaScript: Comparing Web TechnologiesApr 23, 2025 am 12:05 AM

HTML, CSS and JavaScript are the core technologies for building modern web pages: 1. HTML defines the web page structure, 2. CSS is responsible for the appearance of the web page, 3. JavaScript provides web page dynamics and interactivity, and they work together to create a website with a good user experience.

HTML as a Markup Language: Its Function and PurposeApr 22, 2025 am 12:02 AM

The function of HTML is to define the structure and content of a web page, and its purpose is to provide a standardized way to display information. 1) HTML organizes various parts of the web page through tags and attributes, such as titles and paragraphs. 2) It supports the separation of content and performance and improves maintenance efficiency. 3) HTML is extensible, allowing custom tags to enhance SEO.

The Future of HTML, CSS, and JavaScript: Web Development TrendsApr 19, 2025 am 12:02 AM

The future trends of HTML are semantics and web components, the future trends of CSS are CSS-in-JS and CSSHoudini, and the future trends of JavaScript are WebAssembly and Serverless. 1. HTML semantics improve accessibility and SEO effects, and Web components improve development efficiency, but attention should be paid to browser compatibility. 2. CSS-in-JS enhances style management flexibility but may increase file size. CSSHoudini allows direct operation of CSS rendering. 3.WebAssembly optimizes browser application performance but has a steep learning curve, and Serverless simplifies development but requires optimization of cold start problems.

See all articles