Enable New CSS Support by Default

packages/next/next-server/server/config.ts

@@ -42,7 +42,7 @@ const defaultConfig: { [key: string]: any } = {
       (Number(process.env.CIRCLE_NODE_TOTAL) ||
         (os.cpus() || { length: 1 }).length) - 1
     ),
-    css: false,
+    css: true,
     documentMiddleware: false,
     granularChunks: true,
     modern: false,
@@ -109,7 +109,11 @@ function assignDefaults(userConfig: { [key: string]: any }) {
   if (result.experimental) {
     if (result.experimental.css) {
       // The new CSS support requires granular chunks be enabled.
-      result.experimental.granularChunks = true
+      if (result.experimental.granularChunks !== true) {
+        throw new Error(
+          `The new CSS support requires granular chunks be enabled.`
+        )
+      }
     }
 
     if (typeof result.experimental.basePath !== 'string') {

test/integration/chunking-minimal/next.config.js

@@ -1,6 +1,5 @@
 module.exports = {
   experimental: {
     modern: true,
-    granularChunks: true,
   },
 }

test/integration/chunking/next.config.js

@@ -1,9 +1,6 @@
 const BundleAnalyzerPlugin = require('webpack-bundle-analyzer')
   .BundleAnalyzerPlugin
 module.exports = {
-  experimental: {
-    granularChunks: true,
-  },
   webpack(config) {
     config.plugins = config.plugins || []
     config.plugins.push(

test/integration/css-fixtures/next.config.js

@@ -3,11 +3,6 @@ module.exports = {
     // Make sure entries are not getting disposed.
     maxInactiveAge: 1000 * 60 * 60,
   },
-  experimental: {
-    css: true,
-    // Intentionally set false to ensure we force to true.
-    granularChunks: false,
-  },
   webpack(cfg) {
     cfg.devtool = 'source-map'
     return cfg