feat(bundler-vite): configure postcss by default

Author: meteorlxy

packages/@vuepress/bundler-vite/package.json

@@ -35,6 +35,9 @@
     "@vuepress/core": "2.0.0-beta.15",
     "@vuepress/shared": "2.0.0-beta.7",
     "@vuepress/utils": "2.0.0-beta.15",
+    "autoprefixer": "^10.2.5",
+    "postcss": "^8.3.0",
+    "postcss-csso": "^5.0.1",
     "rollup": "^2.50.1",
     "vite": "^2.3.4",
     "vue": "^3.0.11",

packages/@vuepress/bundler-vite/src/plugin/createPlugin.ts

@@ -60,6 +60,14 @@ export const createPlugin = ({
       resolve: {
         alias: await resolveAlias({ app }),
       },
+      css: {
+        postcss: {
+          plugins: [
+            require('autoprefixer'),
+            ...(isBuild ? [require('postcss-csso')] : []),
+          ],
+        },
+      },
       server: {
         host: app.options.host,
         port: app.options.port,