config-overrides.js

module.exports = function override(config, env) {
    require('react-app-rewire-postcss')(config, {
        plugins: loader => [
            require('postcss-flexbugs-fixes'),
            require('postcss-preset-env')({
                autoprefixer: {
                    flexbox: 'no-2009',
                },
                stage: 3,
            }),
            require('postcss-aspect-ratio-mini')({}),
            require('postcss-px-to-viewport')({
                viewportWidth: 750, // (Number) The width of the viewport.
                viewportHeight: 1334, // (Number) The height of the viewport.
                unitPrecision: 3, // (Number) The decimal numbers to allow the REM units to grow to.
                viewportUnit: 'vw', // (String) Expected units.
                selectorBlackList: ['.ignore', '.hairlines','am-'], // (Array) The selectors to ignore and leave as px.
                minPixelValue: 1, // (Number) Set the minimum pixel value to replace.
                mediaQuery: false // (Boolean) Allow px to be converted in media queries.
            }),
            require('postcss-write-svg')({
                utf8: false
            }),
            require('postcss-viewport-units')({}),
            require('cssnano')({
                preset: "advanced",
                autoprefixer: false,
                "postcss-zindex": false
            })
        ]
    });
    return config;
}