Small fixes (#196)

public/postcss.config.js

@@ -0,0 +1,12 @@
+module.exports = {
+  plugins: {
+    'postcss-import': {},
+    'tailwindcss/nesting': {},
+    tailwindcss: {
+      config: "./public/tailwind.config.js",
+    },
+    autoprefixer: {},
+    'postcss-selector-namespace': {namespace() {return (process.env.EMBED) ? '.opengist-embed' : '';}},
+    cssnano: {},
+  },
+}