TLDR: Theme Kendo UI widgets based on Bootstrap.
Longer version: The project aims to provide a Bootstrap theme for Kendo UI widgets, that uses the same variables as Bootstrap to achieve mostly the same appearance and size.
Install build dependencies via npm install. Run npm run build to build the css.
All variable handling happens in _bootstrap-map.scss and it loads Bootstrap variables from the default location e.g. node_modules/bootstrap/scss/_variables.scss.
If you have customized version of Bootstrap, you need to specify the location in _bootstrap-map.scss. Then build as usual.
Since Bootstrap is loaded as npm module pointing directly to the v4 branch it's not impossible for something to break after update.
If it's a mapped variable, you can patch it directly in _bootstrap-map.scss. If it's explicit variable, you need to patch all files.
In any case, you can open an issue.
To ensure some sort of compatibility, Bootstrap variables are mapped locally. Further more, that enables us to use a ad-hoc micro framework based on primitive widgets e.g. button, input, node etc.
Not all variables are mapped though. Some, like $tooltip-arrow-width, used in tooltip, are referenced explictly, because they don't fit within the aforementioned framework.