What Is CSS Code?

CSS3 is an upgraded version of CSS (Cascading Style Sheets) technology. It was developed in 1999. On May 23, 2001, the W3C completed the working draft of CSS3, which mainly includes box models, list modules, hyperlink methods, language modules, backgrounds, Border, text effects, multi-column layout and other modules ^[1] .

As early as 2001, the W3C completed the draft specification of CSS3. A new feature of the CSS3 specification is that it is divided into several independent modules. On the one hand, it is more convenient to update and release the specifications in a timely manner, and adjust the content of the modules in a timely manner. These modules are independently implemented and released, which also lays the foundation for future expansion of CSS. On the other hand, due to the limitations of supported device and browser vendors, there is no equipment or vendors can choose to support some modules, support a subset of CSS3, which is conducive to the promotion of CSS3 ^[3]

CSS3 programming tools are the same as CSS. Any kind of text editing tool can be used to write, such as: Windows Notepad, Notepad; or other special tools for editing webpage text ^[28]

The principle of CSS3 is the same as that of CSS. It is a custom style sheet selector in a web page, and then a large number of these selectors are referenced in the web page. ^[29]

The syntax of CSS3 is based on the previous version of CSS. It allows users to specify specific HTML elements in tags without using redundant classes, IDs, or JavaScript. Most of the CSS selectors are not newly added in CSS3, but have not been widely used in previous versions. Advanced selectors are useful if you want to try to achieve a clean, lightweight tag and a better separation between structure and performance. They can reduce the number of classes and IDs in tags and make it easier for designers to maintain Style sheet ^[31]

There are many new features of CSS3, such as

1. Reduce development and maintenance costs

Before the emergence of CSS3, in order to achieve a rounded corner effect, developers often needed to add additional HTML tags and use one or more images to complete it. However, using CSS3 requires only one tag, which can be done using the border-radius property in CSS3 . In this way, CSS3 technology can free people from the work of drawing, cutting and optimizing pictures. If you need to adjust the radian of the rounded corners or the color of the rounded corners later, using CSS2.1, you need to draw from the beginning and cut the drawing to achieve it. With CSS3, you can quickly modify the border-radius property.

The animation features provided by CSS3 allow developers to stay away from JavaScript before implementing some dynamic buttons or dynamic navigation, so that developers do not need to spend a lot of time writing scripts or finding suitable script plugins to adapt to some dynamic website effects.

Improve page performance

Many CSS3 technologies become "substitutes" for pictures by providing the same visual effects. In other words, reducing the number of extra tags nesting and the number of pictures used in web development means that users will download more content. Less, the page will load faster. In addition, fewer images, scripts, and Flash files can reduce the number of HTTP requests a user has when visiting a Web site, which is one of the best ways to increase page load speed. And using CSS3 to make a graphical website does not require any pictures, which greatly reduces the number of HTTP requests and improves the loading speed of the page. For example, the CSS3 animation effect can reduce HTTP requests for JavaScript and Flash files, but it may require the browser to perform a lot of work to complete the rendering of this animation effect, which may cause the browser to respond slowly and cause users to lose. Therefore, you need to think carefully when using some complex special effects. In fact, many CSS3 technologies can greatly improve the performance of the page in any case ^[44] .

CSS3 will be fully backward compatible, so there is no need to modify the design to keep them working. Web browsers will also continue to support CSS2 ^[45] .