Selector
The rule structure of the selector includes: selector and declaration block. Each declaration block is an attribute key-value pair (remember that each declaration block is best added Ending with semicolon)
p.warning { font-weight:bold; /*其class属性包含词warning的所有段落*/ /*记住解释一般是从左到右读*/ } .warning.urgent { background:red; /*class同时包含warning和urgent的所有元素 其中warning和urgent class没有顺序之分*/ /*选择器当中是没有空格的,如果有空格就成了子元素选择器了*/ } img[alt] { font-weight:bold; /*所有带有alt属性的图像*/ } a[href="http://www.w3.org"][title="W3C Home"] { font-size:20px; /*href值为http://www.w3.org和title值为W3C Home的a链接-------属性值完全匹配才行*/ } span[class~="barren"] { font-style:initial; /*根据属性值中出现的一个用空格分隔的词来完成选择--部分选择值 记住是以空格分隔的一个词*/ }
Substring matching attribute selector
Specific attribute selection type
Link pseudo-class
You may know that the :link and :visited pseudo-class selectors are functionally equivalent to the link and vlink of the body attribute .
Dynamic pseudo-class
Possibly using the wrong first-child
/*这也就是为什么从右向左翻译解释的原因*/ p:first-child { font-weight:bold; /*作为某元素的第一个子元素的所有p元素设置为粗体*/ } li:first-child { text-transform:uppercase; /*作为某元素的第一个子元素的所有li元素变为大写*/ }
Language selector
*:lang(fr) { font-style:italic; }
Pseudo element selector
p:first-letter { color:red;/*让段落的第一个字母变成红色*/ } p:first-line { color:purple;/*让段落的第一行变成紫色*/ } h3:before { content:"[["; color:silver;/*在每个h3元素前加一对银色的中括号*/ } h3:after { content:" The end.";/*在h3元素后固定插入...*/ }

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 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 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.

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.

HTMLisnotaprogramminglanguage;itisamarkuplanguage.1)HTMLstructuresandformatswebcontentusingtags.2)ItworkswithCSSforstylingandJavaScriptforinteractivity,enhancingwebdevelopment.

HTML is the cornerstone of building web page structure. 1. HTML defines the content structure and semantics, and uses, etc. tags. 2. Provide semantic markers, such as, etc., to improve SEO effect. 3. To realize user interaction through tags, pay attention to form verification. 4. Use advanced elements such as, combined with JavaScript to achieve dynamic effects. 5. Common errors include unclosed labels and unquoted attribute values, and verification tools are required. 6. Optimization strategies include reducing HTTP requests, compressing HTML, using semantic tags, etc.

HTML is a language used to build web pages, defining web page structure and content through tags and attributes. 1) HTML organizes document structure through tags, such as,. 2) The browser parses HTML to build the DOM and renders the web page. 3) New features of HTML5, such as, enhance multimedia functions. 4) Common errors include unclosed labels and unquoted attribute values. 5) Optimization suggestions include using semantic tags and reducing file size.

WebdevelopmentreliesonHTML,CSS,andJavaScript:1)HTMLstructurescontent,2)CSSstylesit,and3)JavaScriptaddsinteractivity,formingthebasisofmodernwebexperiences.


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