CSS样式之优先级 - 猴子猿
说到到css的样式优先级，今天偶再来回顾下，从css的样式优先级可分为两个部分：
1、从CSS代码放置的位置看权重优先级：
内联样式 > 内部嵌入样式 >外联样式
2、从样式选择器的权重优先级：
Important > 内联样式 > ID > 类、伪类、属性选择器 > 标签、伪元素 > 通配符
今儿，我们重点来看看第2点—样式选择器。
请看以下代码：
<span style="color: #0000ff;"><span style="color: #ff00ff;">DOCTYPE html</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>css<span style="color: #0000ff;"></span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">meta </span><span style="color: #ff0000;">http-equiv</span><span style="color: #0000ff;">="Content-Type"</span><span style="color: #ff0000;"> content</span><span style="color: #0000ff;">="text/html; charset=utf-8"</span><span style="color: #0000ff;">/></span>
<span style="color: #0000ff;"><span style="color: #800000;">style</span><span style="color: #0000ff;">></span><span style="background-color: #f5f5f5; color: #800000;">
div.class1 </span><span style="background-color: #f5f5f5; color: #000000;">{</span><span style="background-color: #f5f5f5; color: #ff0000;">
background</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">pink</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="background-color: #f5f5f5; color: #000000;">}</span><span style="background-color: #f5f5f5; color: #800000;">
.class2 </span><span style="background-color: #f5f5f5; color: #000000;">{</span><span style="background-color: #f5f5f5; color: #ff0000;">
background</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">green</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #0000ff;"></span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"></span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="class1 class2"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:100px;height:100px;"</span><span style="color: #0000ff;">></span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"></span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"></span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span></span></span></span></span></span></span></span>运行代码，效果图如下：
是粉红色。按照上面的说法class1、class2不都属于类嘛。既然优先级一样，那不就应该是后面的class2（绿色）覆盖住class1（粉红色）吗？
是的。类是属于同一级，但是div.class1和.class2的优先权重是不一样的。
请看下表：
|
选择器 |
权重 |
|
!important |
1,0,0,0 |
|
ID |
0,1,0,0 |
|
类、伪类、属性选择器 |
0,0,1,0 |
|
标签、伪元素 |
0,0,0,1 |
|
通配符 |
0,0,0,0 |
当我们看到html代码时，不要单一看它调用的是什么样式，比如上面的class1、class2在放在div标签上时，都一样，类嘛
但是，其实它们的权重是不一样的。所以要追踪到css样式中，查看它们的权重。
这个权重的计算方法就是利用上面表中对应的权重值，叠加，得到最终值。值越大，权重就越大，从而优先级也就越高咯。
如上面代码中的class1、class2：
结合上面中列出的权重，从而可得class1和class2的权重
class1 = div(0001)+.class1(0010) = 0011
class2 = .class2(0010) = 0010
class1的权重大于class2的权重，从而class1的优先级就高于class2咯。
所以，
下面列举了几个css表达式的权重值，自我测试下：
|
css选择器表达式 |
权重值 |
|
h1 + *[rel = up ] |
0011 |
|
li.red.level |
0021 |
|
#test:not(ii) |
0110 |
|
#test:before |
0101 |
好了，那当样式的优先级一样呢？那就得看它们出现的顺序了。后出现的覆盖前面的。
注意：是样式表中的顺序，而不是html标签中class出现的顺序。
如下：
<span style="color: #0000ff;"><span style="color: #ff00ff;">DOCTYPE html</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>css<span style="color: #0000ff;"></span><span style="color: #800000;">title</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">meta </span><span style="color: #ff0000;">http-equiv</span><span style="color: #0000ff;">="Content-Type"</span><span style="color: #ff0000;"> content</span><span style="color: #0000ff;">="text/html; charset=utf-8"</span><span style="color: #0000ff;">/></span>
<span style="color: #0000ff;"><span style="color: #800000;">style</span><span style="color: #0000ff;">></span><span style="background-color: #f5f5f5; color: #800000;">
.class2 </span><span style="background-color: #f5f5f5; color: #000000;">{</span><span style="background-color: #f5f5f5; color: #ff0000;">
background</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">green</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="background-color: #f5f5f5; color: #000000;">}</span><span style="background-color: #f5f5f5; color: #800000;">
.class1 </span><span style="background-color: #f5f5f5; color: #000000;">{</span><span style="background-color: #f5f5f5; color: #ff0000;">
background</span><span style="background-color: #f5f5f5; color: #000000;">:</span><span style="background-color: #f5f5f5; color: #0000ff;">pink</span><span style="background-color: #f5f5f5; color: #000000;">;</span>
<span style="background-color: #f5f5f5; color: #000000;">}</span>
<span style="color: #0000ff;"></span><span style="color: #800000;">style</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"></span><span style="color: #800000;">head</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"><span style="color: #800000;">div </span><span style="color: #ff0000;">class</span><span style="color: #0000ff;">="class1 class2"</span><span style="color: #ff0000;"> style</span><span style="color: #0000ff;">="width:100px;height:100px;"</span><span style="color: #0000ff;">></span><span style="color: #800000;">div</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"></span><span style="color: #800000;">body</span><span style="color: #0000ff;">></span>
<span style="color: #0000ff;"></span><span style="color: #800000;">html</span><span style="color: #0000ff;">></span></span></span></span></span></span></span></span>运行上述代码，页面显示结果为粉色，而不是绿色！！
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1676
14
1429
52
1333
25
1278
29
1257
24
HTML: The Structure, CSS: The Style, JavaScript: The Behavior
Apr 18, 2025 am 12:09 AM
The roles of HTML, CSS and JavaScript in web development are: 1. HTML defines the web page structure, 2. CSS controls the web page style, and 3. JavaScript adds dynamic behavior. Together, they build the framework, aesthetics and interactivity of modern websites.
The Future of HTML, CSS, and JavaScript: Web Development Trends
Apr 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.
The Future of HTML: Evolution and Trends in Web Design
Apr 17, 2025 am 12:12 AM
The future of HTML is full of infinite possibilities. 1) New features and standards will include more semantic tags and the popularity of WebComponents. 2) The web design trend will continue to develop towards responsive and accessible design. 3) Performance optimization will improve the user experience through responsive image loading and lazy loading technologies.
HTML vs. CSS vs. JavaScript: A Comparative Overview
Apr 16, 2025 am 12:04 AM
The roles of HTML, CSS and JavaScript in web development are: HTML is responsible for content structure, CSS is responsible for style, and JavaScript is responsible for dynamic behavior. 1. HTML defines the web page structure and content through tags to ensure semantics. 2. CSS controls the web page style through selectors and attributes to make it beautiful and easy to read. 3. JavaScript controls web page behavior through scripts to achieve dynamic and interactive functions.
HTML vs. CSS and JavaScript: Comparing Web Technologies
Apr 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: Is It a Programming Language or Something Else?
Apr 15, 2025 am 12:13 AM
HTMLisnotaprogramminglanguage;itisamarkuplanguage.1)HTMLstructuresandformatswebcontentusingtags.2)ItworkswithCSSforstylingandJavaScriptforinteractivity,enhancingwebdevelopment.
Beyond HTML: Essential Technologies for Web Development
Apr 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 is the difference between <strong>, <b> tags and <em>, <i> tags?
Apr 28, 2025 pm 05:42 PM
The article discusses the differences between HTML tags , , , and , focusing on their semantic vs. presentational uses and their impact on SEO and accessibility.
