The theme is still separate from the rest, but it will be easier for you to overwrite styles in Mockup patterns, since we gave up the isolation. The patterns are using the same bootstrap styles you have in the theme. Or if you don't use a bootstrap based theme, you can style it in a diffrent way or combine using the boostrap styles for the patterns and have your own styles for the general layout.
Staticresources contains the core resources in one or more bundles, as it is in Plone 5.2. It's not final, but we will properly have a webpack config in this package to build it. But most of the components are part of mockup where sofar we have the main webpack config to bundle them. Since patternslib is already available as npm package, we could do the same with mockup, so that one can include them easily in webpack or other bundlers and bundle them together with other project related resources.
All resources are still registered in the resource registry similar to who it was in Plone 4.
So we will have only bundles, which are either plain css/js or somehow compiled outsite of Plone before. Overriding existing CSS is not hard, but if you want to change JS components, you have to replace them with you own version. We might decouple some patterns into separate npm package in the process, so it will be easier to replace or improve them.
If webpack federated modules are workign out for us, we might be able to resolve dependencies for addons too.
The iconresolver, uses a icon name in the url to lookup the icon resource url from the plone.registry. The icons are deployed and registered in staticresources and can be overriden via genic setup as usual. @santonelli currently works on a collective package which registeres fontawesome icons enstead of the default bootstrap icons.
But the icon resolver still needs some documentation.
Last, though it should be on every paragraph: million thanks for the work on keeping the > Plone Classic alive and working! Not everyone wants/can move to volto.
Thx, i think so too however, we could use more support.
Right now we are a smal group of people doing most of the work, which slowes us down.