I understand the "starting point" part but I find the emphasis on "classless" interesting: you basically have to introduce a non-element selector as soon as you want make even the smallest layout change.
For anything beyond a single page document, I find something like matcha.css (https://matcha.mizu.sh, you can even pick your custom build on the same page) a practical starting point if you want to stay close to the elements.
For anything beyond a single page document, I find something like matcha.css (https://matcha.mizu.sh, you can even pick your custom build on the same page) a practical starting point if you want to stay close to the elements.