PostCSS is a tool for transforming styles with JS plug-ins.
# To parse and transform a CSS file:
postcss <path/to/file>
# To parse and transform a CSS file and output to a specific file:
postcss <path/to/file> --output <path/to/file>
# To parse and transform a CSS file and output to a specific directory:
postcss <path/to/file> --dir <path/to/directory>
# To parse and transform a CSS file in-place:
postcss <path/to/file> --replace
# To specify a custom PostCSS parser:
postcss <path/to/file> --parser <parser>
# To specify a custom PostCSS syntax:
postcss <path/to/file> --syntax <syntax>
# To watch for changes to a CSS file:
postcss <path/to/file> --watch
# To display available options and examples:
postcss --help