This is not a question but a call out to just a little bit of what @StPaulTim and his team have done for the backdrop community. Today, I stumbled upon a demo theme switcher site where users can scroll down to the footer and select one of a number of different backdrop core and contrib themes to see what they look like. Very nicely done. https://themeswitcher.simplo.site/
Recent comments
I think I've got a handle on Layouts. What is the difference between Cards and Blocks?
Themes: anything like ZEN?
I don't think I said that I liked Zen :-) It's just that I used it on a couple of fairly large sites and was comfortable with it. Learning layouts has got to be easier than learning D10. I...
Themes: anything like ZEN?
Is it just for generating invoices... do you want to track who owes what, or allocate payments, product reports for overdue invoice etc... If it's just invoices, then cooking up a new...
Using Backdrop CMS to generate invoices
The Stripe module has support for webform. You could probably do what they are after with that and customise the output.
Using Backdrop CMS to generate invoices
I used Zen a lot with Drupal 7 as well and liked it. There is no port of Zen, in fact not many Drupal themes have been ported to Backdrop CMS, because theming in Backdrop is quite different from...
Themes: anything like ZEN?