CSS-N (CSS Next) is a set of CSS properties and guidelines that are designed to improve the quality and flexibility of CSS. The latest version, CSS-N 4, was released in 2021 and provides a large number of new features and improvements over previous versions.

One of the key features of CSS-N 4 is the introduction of the `css-n-4mod0` property, which allows developers to specify the initial value of a property using a combination of digits and letters. This property is particularly useful when working with complex CSS queries or designs that require unique values for various elements.

The `css-n-4mod0` property is specified using a combination of digits and letters, such as `4mod0` for the value `4 mod 0` which is equal to 0. The `mod` operator allows you to perform calculations with a value and returns the result as a percentage.

In addition to the `css-n-4mod0` property, CSS-N 4 also provides a large number of other new features and improvements, such as the introduction of the `css-n-4` property, which allows you to specify the base value of a property and the `css-n-4-配合` property, which allows you to specify a combination of properties to achieve a specific result.

Overall, the `css-n-4mod0` property is a powerful tool that can help developers to improve the quality and flexibility of their CSS designs. With the introduction of new features and improvements over previous versions, CSS-N is becoming an increasingly important and valuable resource for CSS developers.