By stefan.r on
Change record status: 
Published (View all published change records)
Project: 
Drupal core
Introduced in branch: 
7.x
Introduced in version: 
7.51
Issue links: 
https://www.drupal.org/node/2009584
Description: 

A new allow_css_double_underscores variable has been added to allow for double underscores in CSS identifiers.

In order to allow CSS identifiers to contain double underscores (.example__selector) for Drupal's BEM-style naming standards, this variable can be set to TRUE. Note that if you change this value in existing sites, existing page styles may be broken.

Also see default.settings.php and drupal_clean_css_identifier().

Impacts: 
Module developers
Themers