Explanation:

The CSS padding property specifies the space between the element's content and its border. The padding property can take any non-negative value, including zero. However, negative values are not allowed in the padding property.

Reasons why negative values are not allowed in padding property:

1. It violates the box model: The padding property is part of the box model, which defines the size and position of an element. Negative padding values violate the box model by making the element's content overlap with its border or margin.

2. It causes layout problems: Negative padding values can cause layout problems, such as overlapping content, misalignment, or unexpected spacing, which can make the website look unprofessional and confusing.

3. It reduces accessibility: Negative padding values can reduce accessibility by making the website harder to read or navigate for users with disabilities or different devices.

Conclusion:

In conclusion, negative values are not allowed in the padding property because they violate the box model, cause layout problems, and reduce accessibility. It is important to use positive padding values that enhance the design and functionality of the website.