Add embedded gists & JSON gist data/metadata (#179)

package.json

@@ -23,9 +23,11 @@
     "github-markdown-css": "^5.5.0",
     "nodemon": "^2.0.22",
     "postcss": "^8.4.13",
+    "postcss-cli": "^11.0.0",
     "postcss-cssnext": "^3.1.1",
     "postcss-import": "^15.1.0",
     "postcss-loader": "^7.1.0",
+    "postcss-selector-namespace": "^3.0.1",
     "sass": "^1.62.1",
     "sugarss": "^4.0.1",
     "tailwindcss": "^3.2.7",