The list of supported CSS and Less functions is growing quite large, and it's very easy to miss a typo.

This rule checks each function name to make sure that it is a known CSS or Less function. All vendor-prefixed functions are ignored because vendors may add in their own functions at any point in time.

Noncompliant Code Example

.mybox {
  color: rgb(255,0,51);
  color: hello(100); /* Noncompliant: 'hello' isn't a known function */
}

Compliant Solution

.mybox {
  color: rgb(255,0,51); /* Compliant: 'rgb' is a known function */
  color: -moz-linear-gradient(top, hsl(0, 80%, 70%), #bada55); /* Compliant: '-moz-linear-gradient' is a vendor function */
}

List of Known Functions

CSS

Less