.postcssrc.js

module.exports = {
  plugins: [
    require('cssnano')({
      preset: [
        'advanced',
        {
          autoprefixer: { add: true, exclude: false },
          discardComments: { removeAll: true, exclude: false },
          autoprefixer: false,
          calc: false,
          colormin: false,
          convertValues: false,
          discardDuplicates: true,
          discardEmpty: true,
          discardOverridden: true,
          discardUnused: true,
          mergeIdents: false,
          mergeLonghand: false,
          mergeRules: false,
          minifyFontValues: false,
          minifyGradients: false,
          minifyParams: false,
          minifySelectors: false,
          normalizeCharset: false,
          normalizeDisplayValues: false,
          normalizePositions: false,
          normalizeRepeatStyle: false,
          normalizeString: false,
          normalizeTimingFunctions: false,
          normalizeUnicode: false,
          normalizeUrl: false,
          normalizeWhitespace: false,
          orderedValues: false,
          reduceIdents: false,
          reduceInitial: false,
          reduceTransforms: false,
          svgo: false,
          uniqueSelectors: false,
          zindex: false
        }
      ]
    })
  ]
};