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