twbs/bootstrap ? reverse-engineered prompt

Build me a comprehensive front-end framework that makes it easy to create responsive, mobile-first websites. It should include a whole library of pre-styled HTML and CSS components like buttons, forms, navbars, cards, and alerts. A key part of this should be a flexible responsive grid system for creating layouts.

I want it to be built with Sass, so developers can easily customize things like the color scheme, fonts, and spacing. It also needs some JavaScript plugins to power interactive components like dropdown menus, modals, and carousels.

The final output should be a set of compiled and minified CSS and JavaScript files that someone can easily include in their project. Also, please set up a documentation website that shows all the components with code examples so people can see how to use them.