I cannot find much if any info or support for Backdrop when it comes to theming questions.

Just wondering if I have a question like:

how to add a class to nav li?

If I cannot find the answer in any Backdrop forums, will the same question being answered in a Drupal 7 forum work for me? (e.g. via drupal.org forums, or stackoverflow and Drupal Answers forms)?



Generally Drupal 7 solutions should work for Backdrop too. I often search for Drupal 7 fixes for Backdrop problems, because as you say there's not much info for Backdrop yet (blog posts. forums, etc.). Just be aware of what's changed between Backdrop and Drupal (https://api.backdropcms.org/change-records), and alter the solution accordingly.

Ok awesome cheers for that @BWPanda

We have a upcoming virtual user group on the topic of creating themes for Backdrop CMS. https://backdropcms.org/news/events/virtual-user-group-creating-themes-and-front-end-development

I think that most things that worked for themes in Drupal 7 will also work in Backdrop CMS. But, there are a number of new options that you will not find in Drupal 7 forums. 

The separation of layouts from the theme in Backdrop CMS was the most difficult thing for me to adjust to on my first site. So, keep the Backdrop CMS layout system in place while theming to be sure that you are fully leveraging it. 

Please, do ask questions about theming in this forum so that future you will be able to find the answers here (and future me).