Yep, because this is part of the new composer markup. New styles, tied to these new IDs, are within https://github.com/borjasalguero/gaia/blob/composer_flex/apps/sms/style/composer.css 
This is a separate css which contains the old styles needed for the new composer.

Im using new IDs, because markup is not the same (it contains more levels). Is there any issue about it?