how to use css

CSS is a style sheet language used for web design that controls how HTML or XHTML appears and is formatted. CSS is an important part of WEB front-end development, and mastering CSS is an essential skill for today's front-end development.

So, how to use CSS? This article will introduce the basic usage and common rules of CSS to help beginners quickly master CSS.

1. Create CSS file
   First, you need to create a CSS file. It can be created using a text editor (such as Notepad, Sublime Text, etc.) and saved as a .css file. Typically, you save the CSS file in a separate file and then use the element in HTML to connect the CSS file to the HTML page.
2. CSS Selectors
   The most common selector in CSS is the element selector, which represents the type of markup you want to apply the style to (such as h1, p, etc.). Prefixing the selector name with "#" indicates an ID selector, while prefixing the name with "." indicates a class selector.

For example, to add a style to the element with the id of "header", the CSS code is as follows:

#header{
  background-color: #ccc;
  width: 100%;
}

3. CSS properties
   In CSS, properties Used to specify the style to be applied to the element. For example, the following CSS style will set the font size to 16 pixels for all p tags:

   p{
     font-size: 16px;
   }

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   The property can also accept multiple values. For example, the following CSS rule will set 4 values ​​for the margin attribute of an element:

   margin: 10px 5px 15px 20px;

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   The first value is top padding, the second is right padding, the third is bottom padding, and the fourth is Left padding. If left padding is not provided, it defaults to the same as right padding; if bottom padding is not provided, it defaults to the same as top padding.

4. CSS Style Sheet
   For large websites, it is recommended to divide the style sheet into several parts for better management. The most common approach is to divide the website's style into various different style sheets, each controlling a different part of the website.

For example, a typical website may have some style sheets: the website global style sheet is responsible for the style of the entire website, navigation bar, header, footer, etc.; another style sheet is responsible for the internal pages. Styles; there is also a typical stylesheet responsible for responsive design, allowing the website to adapt to the different screen sizes of various devices.

5. Using CSS frameworks and preprocessors
   The CSS framework is a set of common style sheets and rules that can speed up website styling. Preprocessors are tools that enhance the functionality of CSS, such as LESS, SASS, and Stylus. They allow developers to control the style of the website using variables, functions, and nested rules.

For example, here are some popular CSS frameworks:

-Bootstrap: One of the most popular and widely used CSS frameworks, it contains various components including forms, navigation, Buttons, grids and layouts.

-Foundation: Another very popular CSS framework that integrates many layout and UI components and provides customization options. Provides more layout customization than Bootstrap.

-Materialize CSS: A CSS framework based on Material Design, with many native controls, it is a very good-looking framework.

Summary
This article introduces the basic usage and common rules of CSS. In addition, there are many other CSS properties and considerations that need to be mastered in practical work. Practice is the best way to learn, by implementing projects and trying different methods to improve your understanding and application of CSS.

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