Add postcss-nested plugin for support old browsers (#22)

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Fixes #

package.json

@@ -21,7 +21,7 @@
         "sync-colors": "node -r dotenv/config -r ts-node/register ./tools/scripts/sync-colors.ts"
     },
     "devDependencies": {
-        "@mappable-world/mappable-cli": "^0.0.34",
+        "@mappable-world/mappable-cli": "^0.0.35",
         "@mappable-world/mappable-types": "^0.0.20",
         "@types/got": "9.6.12",
         "@types/jest": "29.5.3",
@@ -45,6 +45,9 @@
         "jsdom": "22.1.0",
         "lodash": "^4.17.21",
         "nanospinner": "^1.1.0",
+        "postcss": "^8.4.39",
+        "postcss-loader": "^8.1.1",
+        "postcss-nested": "^6.0.1",
         "prettier": "3.0.0",
         "style-loader": "3.3.3",
         "svgo": "^3.2.0",

postcss.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+    plugins: [require('postcss-nested')]
+};