Justin! Thanks again for doing yet another write up and encouraging others to test. Super neat to see what you created. As a fellow rule breaker, this both made me nod my head solemnly and laugh. I promise I wasn’t trying to break you and I understand the sentiment. Coming up with this call for testing nearly broke me likely for similar reasons you ran into when you tried to build your own thing. I’d love to hear a bit more about that experience unless you’re not interested in reliving the horrible memories (truly, no pressure)! In case it helps, I filed a number of issues while I was creating this that you can skim through here: https://github.com/WordPress/gutenberg/issues?q=is%3Aissue+author%3Aannezazu

I also want to note that, while the tests are intentionally constrained right now, I’m keen to do future call for testings where there is a prompt to replicate different aspects of a site. Originally, I was intending to do that with this one by offering three levels of testing (easy, intermediate, advanced header options) before realizing the tooling just isn’t quite there. I went back to the tried and true method after spending a few somewhat frustrating hours in replication mode.

Wide and full block alignments completely disappeared after activating TT1 Blocks.

Can you say more here? I ask because I can still see those options available but there was a recent release of TT1 blocks today to (0.4.5) in order to update to the latest alignment and layout specifications: https://github.com/WordPress/theme-experiments/pull/236 I'm also curious what exactly is causing that white bar in between sections of your header. For now, I'm going to flag this for some themers to see if they have thoughts about what issue might need to be flagged.

As for adjusting the Site Block in general, changing the size actually can be done already thanks to Global Styles. Here’s a short video: https://cloudup.com/c6W7yjZouA0 More options to come with Global Styles too! That’s another aspect of the wider FSE projects that I’m keen to do more testing with.

Your comment around wanting spacing in between navigation items has been discussed in various issues:

https://github.com/WordPress/gutenberg/pull/25339
https://github.com/WordPress/gutenberg/issues/23293

Currently, this is seen as a low priority but there seems to be agreement to not fully on theme styles to provide this and to offer some options people can pick from.

Finally, a nearly said “YES!” outloud to your ending comments around adding a background image. This came up previously in an earlier call for testing and was reported here: https://github.com/WordPress/gutenberg/issues/29238 I added your thoughts in for good measure :)