First of all, let's understand what CSS3 is. CSS3 is an upgrade of CSS technology. CSS3 does not adopt the overall structure, but adopts the modular structure of division of labor and cooperation.
modules in css3
| module name | Function description |
| basic box model | Define various box-related styles |
| line | Define styles associated with various lines |
| speech | Define various sound-related styles, such as properties such as volume, speed of sound, and interval between speeches |
| background and border | Define various styles related to backgrounds and borders |
| text | Define various text-related styles |
| color | Define various color-related styles |
| font |
Define various font-related styles |
| paged media | Define styles for various page metadata such as headers, footers, page counts, etc. |
| cascading and inheritance | Define how to assign values to properties |
| value and units | Uniform positioning of various values and units on the page for use by other modules |
| image values | Define the assignment method to the image element |
more.......
The reason why it is divided into so many modules for management is to avoid the situation that the browser does not fully support a certain module. If there is only one overall structure, the overall structure will be too large, and it is easy to cause incomplete support when supporting it. If the overall structure is divided into several modules, each browser can choose which module to support and which module not to support. When supporting, one module can be fully supported and then another module can be supported to reduce the possibility of incomplete support.