== Why is this an issue?

The W3C specifications define the ``++units++`` that can be used with lengths. A unit that is not part of the list of supported ones is likely to be a typo and will be seen as a UI bug by the user.


This rule raises an issue each time a unit is not officially supported.


=== Noncompliant code example

[source,css]
----
a {
  width: 10pixels; /* Noncompliant; "pixels" is not a valid unit */
}
----


=== Compliant solution

[source,css]
----
a {
  width: 10px;
}
----


== Resources

* https://www.w3.org/TR/css3-values/#lengths[CSS Specification] - Distance units

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Replace XXX by a valid unit.


endif::env-github,rspecator-view[]