The Core Framework team just released version 1.3 which includes CSS variable and class previews and autocomplete drop downs for Bricks and Oxygen. Here is the full changelog.

The latest version of Builderius adds support for the Core Framework and ACSS.

This video walk-through shows using the free version of the Core Framework with vanilla Gutenberg and with Cwicly. It also shows what works and the gotchas, as well as the steps for using it with Cwicly.

The Core Framework is a new toolkit for creating and customizing your own CSS framework. There is a UI for generating CSS classes and variables and there is a WordPress plugin. At launch the Core Framework has WordPress extensions for Gutenberg, Bricks, and Oxygen. This video is a first look at the features and a quick test using the Gutenberg and Bricks extensions.