一、理论:
1.CSS盒模型
a.外盒尺寸计算--高度
element空间高度=内容高度+内距+边框+边距
b.外盒尺寸计算--宽度 element空间宽度=内容宽度+内距+边框+外距
c.内盒尺寸计算--高度
element高度=内容高度+内距+边框
d.内盒尺寸计算--宽度
element宽度=内容宽度+内距+边框
2.box-sizing
a.content-box 默认值
b.border-box 元素维持IE传统的盒模型
c.inherit 使元素继承父元素的盒模型模式
d.此值主要目的是控制元素的总宽度
二、实践:
1.
<meta charset="UTF-8"> <title>Title</title> <style type="text/css"> *{ margin: 0; padding: 0; } .wrapper{ width: 960px; margin-left: auto; margin-right: auto; color:#6bb2ff; font-size: 30px; text-align: center; } #header{ height: 100px; background: #228833; margin-bottom: 10px; } .sidebar{ float:left; width: 220px; margin-right: 20px; margin-bottom: 10px; height: 300px; background: #ebf3fc; } .content{ float:left; width: 720px; height: 300px; background: #ffcc99; margin-bottom: 10px; } #footer{ background: #a6f821; height: 100px; clear: both; } </style> <div class="wrapper"> <div id="header">hedaer</div> <div class="sidebar">left</div> <div class="content">main</div> <div id="footer">footer</div> </div>2.
<meta charset="UTF-8"> <title>Title</title> <style type="text/css"> *{ margin: 0; padding: 0; } .wrapper{ width: 960px; margin-left: auto; margin-right: auto; color:#6bb2ff; font-size: 30px; text-align: center; background: #ffcc99; } #header{ height: 100px; background: #228833; margin-bottom: 10px; padding: 10px; width: 100%; } .sidebar{ float:left; width: 220px; margin-right: 20px; margin-bottom: 10px; height: 300px; background: #ebf3fc; padding: 10px; } .content{ float:left; width: 720px; height: 300px; background: #ffcc99; margin-bottom: 10px; padding: 10px; } #footer{ background: #a6f821; height: 100px; clear: both; padding: 10px; width: 100%; } </style> <div class="wrapper"> <div id="header">hedaer</div> <div class="sidebar">left</div> <div class="content">main</div> <div id="footer">footer</div> </div>3.
<meta charset="UTF-8"> <title>Title</title> <style type="text/css"> *{ margin: 0; padding: 0; } .wrapper{ width: 960px; margin-left: auto; margin-right: auto; color:#6bb2ff; font-size: 30px; text-align: center; background: #ffcc99; } #header{ height: 100px; background: #228833; margin-bottom: 10px; padding: 10px; width: 100%; border: 10px solid darkgray; } .sidebar{ float:left; width: 220px; margin-right: 20px; margin-bottom: 10px; height: 300px; background: #ebf3fc; padding: 10px; border: 10px solid red; } .content{ float:left; width: 720px; height: 300px; background: #ffcc99; margin-bottom: 10px; padding: 10px; border: 10px solid chartreuse; } #footer{ background: #a6f821; height: 100px; clear: both; padding: 10px; width: 100%; border: 10px solid #202189; } </style> <div class="wrapper"> <div id="header">hedaer</div> <div class="sidebar">left</div> <div class="content">main</div> <div id="footer">footer</div> </div>4.
<meta charset="UTF-8"> <title>Title</title> <style type="text/css"> *{ margin: 0; padding: 0; } .wrapper{ width: 960px; margin-left: auto; margin-right: auto; color:#6bb2ff; font-size: 30px; text-align: center; background: #ffcc99; } #header{ height: 100px; background: #228833; margin-bottom: 10px; padding: 10px; width: 100%; border: 10px solid darkgray; -moz-box-sizing: border-box; -webkit-box-sizing: border-box; -o-box-sizing:border-box; -ma-box-sizing:border-box; box-sizing: border-box; } .sidebar{ float:left; width: 220px; margin-right: 20px; margin-bottom: 10px; height: 300px; background: #ebf3fc; padding: 10px; border: 10px solid red; -moz-box-sizing: border-box; -webkit-box-sizing: border-box; -o-box-sizing:border-box; -ma-box-sizing:border-box; box-sizing: border-box; } .content{ float:left; width: 720px; height: 300px; background: #ffcc99; margin-bottom: 10px; padding: 10px; border: 10px solid chartreuse; -moz-box-sizing: border-box; -webkit-box-sizing: border-box; -o-box-sizing:border-box; -ma-box-sizing:border-box; box-sizing: border-box; } #footer{ background: #a6f821; height: 100px; clear: both; padding: 10px; width: 100%; border: 10px solid #202189; -moz-box-sizing: border-box; -webkit-box-sizing: border-box; -o-box-sizing:border-box; -ma-box-sizing:border-box; box-sizing: border-box; } </style> <div class="wrapper"> <div id="header">hedaer</div> <div class="sidebar">left</div> <div class="content">main</div> <div id="footer">footer</div> </div>

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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