ConverseJS theme: Fix margin when hidding avatars.

.stylelintrc.js

@@ -8,7 +8,7 @@ module.exports = {
   rules: {
     'selector-class-pattern': [
       // extending the kebab-case to accept ConverseJS class names.
-      '^([a-z][a-z0-9]*)(-[a-z0-9]+)*(__[a-z]+)?$',
+      '^([a-z][a-z0-9]*)(-[a-z0-9]+)*((__|--)[a-z]+(-[a-z0-9]+)*)?$',
       {
         message: 'Expected class selector to be kebab-case, or ConverseJS-style.',
       }