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How to introduce css into html

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Release： 2023-05-29 19:55:06

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How to introduce CSS into HTML

As the basis of front-end development, the relationship between HTML and CSS complements each other. HTML is responsible for building the page structure and content, while CSS is responsible for adding color and beautifying the page on this basis. So, how to introduce CSS styles into HTML documents? This article will introduce how to introduce CSS and what to pay attention to.

Refer external CSS in the HTML header

This is the most common and recommended way to reference CSS. Taking the common page structure as an example, add a link tag in the HTML header tag:

<!DOCTYPE html>
<html>
  <head>
    <title>标题</title>
    <link rel="stylesheet" type="text/css" href="style.css">
  </head>
  <body>
      页面内容
  </body>
</html>

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Among them, the link tag has three attributes:

rel: represents the style sheet and The relationship of the current document is an external style sheet, and the value is "stylesheet";
type: indicates the MIME type of the style sheet file, and the value is "text/css";
href: indicates The reference path to the style sheet file.

It should be noted here that the path of the href attribute should be based on the current HTML path, not the relative path where the CSS file is located. Assuming that the CSS file is in the same directory as the current HTML, the reference style should be written like this:

<link rel="stylesheet" type="text/css" href="./style.css">

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where "." indicates the current directory, and the file name suffix ".css" cannot be omitted.

Embed internal CSS in the HTML header

In HTML documents, we can embed internal CSS through the style tag. This method inevitably increases the size of the HTML file, but for some simple and small websites, it can save the request and download time of external files and speed up the page response speed. The following is a sample code:

<!DOCTYPE html>
<html>
  <head>
    <title>标题</title>
    <style type="text/css">
      /* CSS样式内容 */
      body {background-color: #F1F1F1;}
      h1 {color: orange;}
    </style>
  </head>
  <body>
      页面内容
  </body>
</html>

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Among them, the content in the style tag has the same format as the external CSS file, except that the style code is written directly inside the style tag. It should be noted that in order to avoid style pollution (CSS styles affecting each other), internal CSS should use meaningful CSS selectors to limit the scope of styles.

Embedding inline styles in HTML elements

Inline styles refer to embedding CSS style code directly into the style attribute of HTML elements. This method is extremely flexible, but it is not conducive to code reuse and maintenance. The following is sample code:

<!DOCTYPE html>
<html>
  <head>
    <title>标题</title>
  </head>
  <body>
    <h1 style="color:orange;">页面标题</h1>
    <p style="font-size:18px;">页面内容</p>
  </body>
</html>

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It should be noted that when using inline styles, you should ensure that the style code does not affect the accessibility (Accessibility) and usability (Usability) of the page. For some styles similar to visual effects, you should use external styles or internal styles.

References:

W3Schools. CSS - External Style Sheets
W3Schools. CSS - Internal Styles
W3Schools. CSS - Inline Styles
Study Notes: Basic Knowledge of HTML and CSS

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