It sounds like there’s some additional configuration/coding you’ve done that might be causing this issue. Your early post mentioned uncss, which IIRC isn’t part of vanilla Sage. I looked up the tool, and it looks like it determines unused CSS by loading your pages in a browser and then examining them using the DOM. I don’t know how you’re configured it but my guess would be that uncss requires a url and is somehow being told example.test is the URL it should be examining. If that’s the cause I’m guessing you might only be seeing this issue on build:production because uncss looks for the production environment, and only executes itself when it sees that (i.e. otherwise it assumes itself to be running in a development environment where it shouldn’t be removing styles). If that is the problem, I don’t think I can help you much because I’m not familiar with that package–although I would recommend looking into PurgeCSS which doesn’t require a url in order to evaluate your code for unused CSS.