This rule template can be used to create rules which will be triggered when an @-rule matches a given regular expression.
For example, one can create a rule with the regular expression (charset|font-face) to match
charset and font-face @-rules (to warn developers not to use them for some reasons for
instance).
Note that, in order to match charset and font-face @-rules regardless of the case, the
(?i) modifier can be prepended to the expression, as in (?i)(charset|font-face).
See Java documentation for detailed regular expression syntax.