Sure enough, this looks great. Found a blog post where someone did the exact same thing. Unlike the Firefox mechanism of usercontent.css which requires a reboot after every change(?) this works dynamically on a page reload. Now trivial to restyle some content which would otherwise not hit a blocklist.

https://darekkay.com/blog/ublock-website-themes/

As someone extremely adverse to plugs, I was unaware ubo (the only plugin I use) was capable of this. Thank you!