The changes introduce the build setup, configuration files, and basic documentation. This adds PostCSS for processing CSS files with import handling and minification, along with NPM scripts and documentation for build commands.

Here's the commit message:

Initialize PostCSS build and project documentation

Build setup includes:
- PostCSS config with import handling and minification
- Build scripts for minified and preview output
- Version banner handling in CSS output
- Project READMEs describing build process
- Basic .gitignore configuration