css is "cascading style sheet", its versions are: 1. CSS1.0, which is the first standard related to style; 2. CSS2.0, this version recommends the separation of content and performance effects Method; 3. CSS2.1, which is slightly modified based on CSS2.0; 4. CSS3, which is the third version of the CSS specification.
The operating environment of this tutorial: windows7 system, HTML5&&CSS3 version, Dell G3 computer.
CSS’s full English name is Cascading Style Sheet, and its Chinese translation is “Cascading Style Sheet”. CSS is mainly a style design language that enriches the content of HTML tags and separates the web page presentation style from the web page structure. You can use CSS to control the display style of the text content, image shape, layout and other appearance in the HTM page.
What is CSS
In the early 1990s, the HTML language was born, and various forms of style sheets also appeared. But as the functionality of HTM increases, foreign languages for defining styles become increasingly meaningless. In 1994, Hakun Li proposed the original proposal of CSS. Bert Bos was designing a browser called Argo at the time, and they decided to collaborate on the design of CSS. Since its development, there have been 4 versions of CSS. The specific introduction is as follows
1.CSS1.0
In December 1991, W3C released the first style-related standard CSS1.0. This version already includes related attributes of font, color and background, text, box, etc.
2.CSS2.0
In May 1985, CSS2.0 was officially launched. What this version recommends is the separation of content and presentation effects, and the use of style sheet structures.
3.CSS2.1
In February 2004, CSS2.1 was officially launched. It is slightly modified based on CSS2.0 and deletes many attributes that are not supported by browsers.
4.CSS3
As early as 2001, W3C began preparing to develop the third edition of the CSS specification. Although the complete, standardized and authoritative CSS3 standard has not yet been finalized, major browsers have begun to support most of its features.
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