When was css3 launched?

CSS3 began to be formulated in 1999. On May 23, 2001, W3C completed the working draft of CSS3. The draft developed a CSS3 development roadmap, listing all modules in detail, and planned to gradually proceed in the future. Specification; mainly includes modules such as box model, list module, hyperlink method, language module, background and border, text effects, etc.

The operating environment of this tutorial: Windows 7 system, CSS3 version, Dell G3 computer.

CSS3 is an upgraded version of CSS (Cascading Style Sheets) technology. It was formulated in 1999. On May 23, 2001, W3C completed the working draft of CSS3; in this draft, a CSS3 development roadmap was formulated. The roadmap lists all modules in detail and plans to gradually standardize them in the future.

A new feature of the CSS3 specification is that it is divided into several independent modules. On the one hand, dividing it into several smaller modules is more conducive to the timely updating and release of specifications, and the timely adjustment of module content. These modules are independently implemented and released, which also lays the foundation for future CSS expansion. On the other hand, due to limitations of supported devices and browser manufacturers, devices or manufacturers can selectively support some modules and support a subset of CSS3, which is conducive to the promotion of CSS3.

The following is a brief explanation of the release time and content of each major module:

• The CSS3 Line module was released on May 15, 2002, which standardizes text lines. Model.

• The CSS3 Lists module was released on November 7, 2002, which standardizes list styles.

• The CSS3 Border module was also released on November 7, 2002, adding a new background border function. This module was later merged into the background module.

• The CSS3 Generated and Replaced Content module was released on May 14, 2003, defining the CSS3 generated and replaced content functions.

• The CSS3 Presentation Levels module was released on August 13, 2003, defining the presentation effect function.

• The CSS3 Syntax module was also released on August 13, 2003, which redefined the basics of CSS syntax.

• The CSS3 Hyperlink Presentation module was released on February 24, 2004, redefining the rules for hyperlink presentation.

• The CSS3 Speech module was released on December 16, 2004, which redefines speech "style" rules.

• The CSS3 Cascading and Inheritance module was released on December 15, 2005, defining CSS cascading and inheritance rules.

• The CSS3 Basic Box module was released on August 9, 2007, which redefines the CSS basic box model rules.

• The CSS3 Grid Positioning module was released on September 5, 2007, defining CSS grid positioning rules.

• The CSS3 Animations module was released on March 20, 2009, defining the CSS animation model.

• The CSS3 3D Transforms module was also released on March 20, 2009, which defines the CSS 3D transformation model.

• The CSS3 Fonts module was released on June 18, 2009, defining CSS font modes.

• The CSS3 Image Values ​​module was released on July 23, 2009, defining the image content display model.

• The CSS3 Flexible Box Layout module was also released on July 23, 2009, which defines a flexible box layout model.

• The CSS3 2D Transforms module was released on December 1, 2009, defining the 2D transformation model.

• The CSS3 Generated Content for Paged Media module was released on April 29, 2010, defining the paged media content model.

• The CSS3 Text module was released on October 5, 2010, defining the text model.

• Also released on October 5, 2010 was the CSS3 Background and Borders module, which repatched the border and background models.

More detailed information can be found at https://www.w3c.org/Style/CSS/current-work.html, which introduces how many modules CSS3 is divided into, CSS3 The current status of all modules and when they will be released.

CSS3 is divided into multiple modules, each module has its own specifications. The advantage of this is:

• The entire CSS3 specification will not be released due to There are some disputes that affect the advancement of other modules.

• For the browser, you can decide which CSS functions are supported based on your needs.

• For W3C developers, targeted updates can be made as needed, making the overall specification more flexible and able to be revised in a timely manner, making it easier to expand new technology-specific .

What are the benefits of using CSS3?

The most obvious thing is that CSS3 can make the page look very flashy and cool, making the website design even better, but its benefits go far beyond that.

In most cases, using CSS3 is not only beneficial to development and maintenance, but also improves website performance. At the same time, it can also increase the accessibility and usability of the website, enable the website to adapt to more devices, and even optimize the website SEO and improve the search ranking results of the website.

1. Reduce development and maintenance costs

Why is CSS3 able to reduce development and maintenance costs?

Let’s look at an example first. A rounded corner effect requires adding additional HTML tags in CSS2 and using one or more images to complete; while using CSS3, it only requires one tag and a border-radius attribute to complete. In this way, CSS3 technology can save people from the work of drawing, cutting and optimizing images.

If you need to adjust the arc or color of the rounded corner later, if you use CSS2, you have to draw and cut the image from scratch to complete it, but using CSS3 can complete these tasks in a few seconds.

CSS3 can also keep us away from a lot of JavaScript script code or Flash. We no longer need to spend a lot of time writing scripts or finding suitable script plug-ins and modifying them to adapt to website special effects.

Finally, some CSS3 techniques can also help simplify the page and make the structure clearer. For example, nesting many div tags and class names to achieve an effect can effectively improve work efficiency, reduce development time, and reduce development costs. For example, to create an overlapping background effect, you need to add div tags and class names in CSS, and put a background image in different divs. Now you can use the new features of CSS3 such as multiple backgrounds and background sizes, and add it to a div tag. can complete these tasks.

2. Improve page performance

When doing Web development, reducing redundant tag nesting and the number of images used means that users will download less content and page loading will be faster. will be faster. In addition, fewer images, scripts, and Flash files allow the website to reduce the number of HTTP requests, which is one of the best ways to improve page loading speed.

Using CSS3 to create a graphical website does not require any images, which can greatly reduce the number of HTTP requests and improve the page loading speed.

Of course, this depends on what technology CSS3 features are used to replace, and it also depends on how CSS3 features are used. For example, CSS3 animation effects can reduce HTTP requests for JavaScript and Flash files, but may require the browser to perform a lot of work to complete the rendering of the animation effects, which may cause the browser to respond slowly and lead to user loss.

Therefore, everyone needs to think carefully when using some complex special effects. However, such phenomena are rare after all.

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