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.