CSS: “padding”: X is not a “padding” value.

A CSS padding property contains a value the validator does not recognize as valid for that property.

The padding shorthand and its longhand variants (padding-top, padding-right, padding-bottom, padding-left) accept only <length>, <percentage>, or the keyword auto (in some contexts). Common causes of this error include:

• Using an invalid unit or misspelling a unit, such as 10xp instead of 10px.
• Omitting the unit on a non-zero value, such as padding: 10 instead of padding: 10px.
• Passing a color, keyword, or other unrelated value, such as padding: red or padding: bold.
• Including extra or misplaced values from a copy-paste error, such as padding: 10px 20px 30px 40px 50px (five values instead of the maximum four).
• Using CSS custom properties or newer syntax in an inline style attribute that the validator's CSS parser does not yet support.

The padding shorthand accepts one to four values, corresponding to the top, right, bottom, and left sides. Each value must be a non-negative length (like 0, 8px, 1em, 2rem) or a percentage.

HTML examples

Invalid padding value

<div style="padding: 10xp;">Content</div>

Fixed padding value

<div style="padding: 10px;">Content</div>

Learn more:

MDN Reference

CSS padding property

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MDN Reference

CSS values and units

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web.dev Article

Learn CSS Box Model

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