feat: add postcss config and deps

bugfix: some unused imports and node-selection component removed for now
update: README.md

package.json

@@ -19,12 +19,16 @@
     "@vue/babel-plugin-jsx": "^1.0.6",
     "@vue/compiler-sfc": "^3.0.5",
     "@vue/eslint-config-typescript": "^7.0.0",
+    "autoprefixer": "^10.2.6",
     "babel-eslint": "latest",
     "eslint": "^7.29.0",
     "eslint-config-prettier": "^8.1.0",
     "eslint-plugin-nuxt": "^2.0.0",
     "eslint-plugin-prettier": "^3.3.1",
     "eslint-plugin-vue": "^7.12.1",
+    "postcss": "^8.3.5",
+    "postcss-cli": "^8.3.1",
+    "postcss-nested": "^5.0.5",
     "prettier": "^2.2.1",
     "typescript": "^4.3.5",
     "vite": "^2.3.8",