Use build tooling to compile the RTL CSS

package.json

@@ -1,28 +1,43 @@
 {
-    "name": "underscores",
-    "version": "1.0.0",
-    "description": "Hi. I'm a starter theme called _s, or underscores, if you like. I'm a theme meant for hacking so don't use me as a Parent Theme. Instead try turning me into the next, most awesome, WordPress theme out there. That's what I'm here for.",
-    "author": "Automattic Theme Team",
-    "license": "GPL-2.0-or-later",
-    "keywords": [
-      "WordPress",
-	  "Theme"
-	],
-    "homepage": "https://github.com/Automattic/_s#readme",
-    "repository": {
-      "type": "git",
-      "url": "git+https://github.com/Automattic/_s.git"
+  "name": "underscores",
+  "version": "1.0.0",
+  "description": "Hi. I'm a starter theme called _s, or underscores, if you like. I'm a theme meant for hacking so don't use me as a Parent Theme. Instead try turning me into the next, most awesome, WordPress theme out there. That's what I'm here for.",
+  "author": "Automattic Theme Team",
+  "license": "GPL-2.0-or-later",
+  "keywords": [
+    "WordPress",
+    "Theme"
+  ],
+  "homepage": "https://github.com/Automattic/_s#readme",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/Automattic/_s.git"
+  },
+  "bugs": {
+    "url": "https://github.com/Automattic/_s/issues"
+  },
+  "devDependencies": {
+    "@wordpress/scripts": "^7.2.0",
+    "node-sass": "^4.13.1",
+    "rtlcss": "^2.5.0"
+  },
+  "rtlcssConfig": {
+    "options": {
+      "autoRename": false,
+      "autoRenameStrict": false,
+      "blacklist": {},
+      "clean": true,
+      "greedy": false,
+      "processUrls": false,
+      "stringMap": []
     },
-    "bugs": {
-      "url": "https://github.com/Automattic/_s/issues"
-    },
-    "devDependencies": {
-        "node-sass": "^4.13.1",
-        "@wordpress/scripts": "^7.2.0"
-    },
-    "scripts": {
-        "compile:css": "node-sass sass/style.scss style.css && node-sass sass/woocommerce.scss woocommerce.css && stylelint '*.css' --fix || true && stylelint '*.css' --fix",
-        "lint:scss": "wp-scripts lint-style 'sass/**/*.scss'",
-        "lint:js": "wp-scripts lint-js 'js/*.js'"
-    }
+    "plugins": [],
+    "map": false
+  },
+  "scripts": {
+    "compile:css": "node-sass sass/style.scss style.css && node-sass sass/woocommerce.scss woocommerce.css && stylelint '*.css' --fix || true && stylelint '*.css' --fix",
+    "compile:rtl": "rtlcss style.css style-rtl.css",
+    "lint:scss": "wp-scripts lint-style 'sass/**/*.scss'",
+    "lint:js": "wp-scripts lint-js 'js/*.js'"
+  }
 }