PostCSS CLI & cssnano example

in.css

h1 {
    display: flex;
}

package.json

{
  "name": "postcss-cli-cssnano-gist",
  "private": true,
  "scripts": {
    "compile": "postcss -c postcss.json",
    "watch": "postcss -c postcss.json -w"
  },
  "devDependencies": {
    "autoprefixer": "^6.3.6",
    "cssnano": "^3.7.0",
    "postcss-cli": "^2.5.2"
  }
}

postcss.json

{
    "use": ["autoprefixer", "cssnano"],
    "input": "in.css",
    "output": "out.css",
    "autoprefixer": {
        "browsers": "> 5%"
    },
    "cssnano": {
        "autoprefixer": false
    }
}