selector-pseudo-element-allowed-list
Specify a list of allowed pseudo-element selectors.
  a::before {}
/**  ↑
 * This pseudo-element selector */
This rule ignores:
- CSS2 pseudo-elements i.e. those prefixed with a single colon
 - selectors that use variable interpolation e.g. 
::#{$variable} {} 
The message secondary option can accept the arguments of this rule.
Options
array|string|regex: ["array", "of", "unprefixed", /pseudo-elements/, "/regex/"]|"pseudo-element"|"/regex/"|/regex/
Given:
["before", "/^--my-/i"]
The following patterns are considered problems:
a::after {}
a::--not-my-pseudo-element {}
The following patterns are not considered problems:
a::before {}
a::--my-pseudo-element {}
a::--MY-OTHER-pseudo-element {}