


Flex achieves perfect centering of sub-blocks
Solution
The parent block uses the display:flex attribute, and the sub-block margin can be adaptively implemented
Code
index.html
<!DOCTYPE html><html lang="zh"><head> <meta charset="UTF-8"> <title>块状元素垂直居中(已知高度)</title> <style> *{margin: 0;padding: 0;} .parent{ display: flex; height:500px; background: #03A1FA; } .child{ width: 100px; height: 100px; margin: auto; background: #BB3713; } /* 这个依赖于设置“margin”值为“auto”值,自动获取伸缩容器中剩余的空间。所以设置垂直方向margin值为“auto”,可以使伸缩项目在伸缩容器的两上轴方向都完全集中。 */ </style></head><body> <div class="parent"> <div class="child">ff</div> </div></body></html>Horizontal and vertical centering of unknown width and height elements
Solution
Use the transform:translate attribute to adjust
Code
index.html
<!DOCTYPE html><html lang="zh"><head> <meta charset="UTF-8"> <title>块状元素水平垂直居中(未知宽高)</title> <style> *{margin: 0;padding: 0;} /*简易版reset,工作环境不推荐使用*/ #container{ position:absolute; top:50%; left:50%; -webkit-transform: translate(-50%,-50%); -ms-transform: translate(-50%,-50%); -o-transform: translate(-50%,-50%); transform: translate(-50%,-50%); background-color: #A4FF00; color:rgb(33, 172, 134); } /*因为不知道宽高度,所以主要用translate属性拉回未知元素XY轴上的位置实现居中*/ /*若是单纯实现未知高度的元素居中,只要用到transform:translateY(-50%)即可实现*/ </style></head><body> <div id="container">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Recusandae obcaecati expedita ducimus, rem laborum veniam qui quo facilis enim. Repellat blanditiis nemo, magnam, sequi illum perferendis consequatur modi maiores quaerat?</div></body></html>flex implements horizontal and vertical centering of the page
scheme
Define the justify-content and align-items attributes of the parent element of the centered element Just set it to center, you need to set enough height, otherwise there will only be a horizontal centering effect
Code implementation
index.html
<!DOCTYPE html><html lang="zh"> <head> <meta charset="UTF-8"> <title>flex实现子块的完美居中</title> <style> * { margin: 0; padding: 0; } .parent { display: flex; justify-content: center; align-items: center; height:900px; background: #03A1FA; } .child { width: 100px; height: 100px; background: #BB3713; } </style> </head> <body> <div class="parent"> <div class="child">啦啦德玛新亚</div> </div> </body></html>

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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