import { postcss } from "https://deno.land/x/fed_dev@0.9.0/deps.ts";
const { Root } = postcss;
Returns a Result instance representing the root’s CSS.
const root1 = postcss.parse(css1, { from: 'a.css' })
const root2 = postcss.parse(css2, { from: 'b.css' })
root1.append(root2)
const result = root1.toResult({ to: 'all.css', map: true })