Hi, thanks for your article on how to include sass and bootstrap into a next.js project. As for the caveat, you can evaluate the process.env.NODE_ENV variable and add the purgecss setting block only in the production environment. For more, see the next.js docs: Customizing Plugins . Here is my postcss.config.js file: module.exports = { plugins: [ 'postcss-flexbugs-fixes', [ 'postcss-preset-env', { autoprefixer: {flexbox: 'no-2009'}, stage: 3, features: {'custom-properties': false}, }, ], ], }; if (process.env.NODE_ENV === 'production') { module.exports.plugins.push([ '@fullhuman/postcss-purgecss', { content: ['./src/**/*.{js,jsx,ts,tsx}', './pages/**/*.{js,jsx,ts,tsx}'], defaultExtractor: (content) => content.match(/[\w-/:]+(?<!:)/g) || [], safelist: ['html', 'body'], }, ]); } In my still empty project that includes bootstrap, I could decrease the size of the .next folder from 6.6 MB to 5.2MB using purgecss in the production build.