Source map options
The CSS node that was the source of the warning.
Function to generate AST by string.
Name of plugin that created this warning. Result#warn will fill it
automatically with Plugin#postcssPlugin value.
Class to generate string by AST.
Object with parse and stringify.
The path where you'll put the output CSS file. You should always set to
to generate correct source maps.
The path of the CSS source file. You should always set
from, because it is used in source map generation and syntax error messages.