I can understand why Q&A layout have different CSS display inside the topic, but can't understand why is that the case with Simplified and Extended categories?

• Simplified:  https://wpforo.com/community/wpforo-showcase/huntsends-qa-community/
• Extended:  https://wpforo.com/community/wpforo-integration/help-with-problem-with-urls-please/

Extended have different avatars shape, non-rounded button, user info, different background style...

Is there a way to unify somehow these two and use only one CSS?