Skip to content
Biome
Docs Blog Playground

noUnknownProperty

Diagnostic Category: lint/correctness/noUnknownProperty

Since: v1.8.0

Sources:

Disallow unknown properties.

This rule considers properties defined in the CSS Specifications and browser specific properties to be known. https://github.com/known-css/known-css-properties#source

This rule ignores:

  • custom variables e.g. --custom-property
  • vendor-prefixed properties (e.g., -moz-align-self, -webkit-align-self)

Examples

Section titled Examples

Invalid

Section titled Invalid
a {
  colr: blue;
}
code-block.css:2:3 lint/correctness/noUnknownProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unknown property is not allowed.
  
    1 │ a {
  > 2 │   colr: blue;
      │   ^^^^
    3 │ }
    4 │ 
  
  ℹ See CSS Specifications and browser specific properties for more details.
  
  ℹ To resolve this issue, replace the unknown property with a valid CSS property.
  
a {
  my-property: 1;
}
code-block.css:2:3 lint/correctness/noUnknownProperty ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unknown property is not allowed.
  
    1 │ a {
  > 2 │   my-property: 1;
      │   ^^^^^^^^^^^
    3 │ }
    4 │ 
  
  ℹ See CSS Specifications and browser specific properties for more details.
  
  ℹ To resolve this issue, replace the unknown property with a valid CSS property.

Valid

Section titled Valid
a {
  color: green;
}
a {
  fill: black;
}
a {
  -moz-align-self: center;
}
Section titled Related links