Add Stylelint configuration.

.gitignore

@@ -7,3 +7,7 @@ coverage/
 
 # Environment configuration
 .env
+
+# NodeJS files
+node_modules/
+pnpm-lock.yaml

package.json

@@ -0,0 +1,21 @@
+{
+  "private": "true",
+  "scripts": {
+    "test": "stylelint 'source/**/*.scss'"
+  },
+  "dependencies": {
+    "modern-normalize": "^1.1.0"
+  },
+  "devDependencies": {
+    "stylelint": "^14.12.1",
+    "stylelint-config-standard-scss": "^5.0.0"
+  },
+  "stylelint": {
+    "extends": [
+      "stylelint-config-standard-scss"
+    ],
+    "rules": {
+      "string-quotes": "single"
+    }
+  }
+}