build: add stylelint

.lintstagedrc

@@ -1,3 +1,7 @@
 {
-  "src/**/*.js|*.config.js": ["eslint --fix", "git add"]
+  "linters": {
+    "*.js": ["eslint --fix", "git add"],
+    "*.{css,scss,html}": ["stylelint --fix", "git add"]
+  },
+  "ignore": ["{dist,docs}/**/*.js", "*.min.*"]
 }

.stylelintrc

@@ -0,0 +1,10 @@
+{
+  "extends": "stylelint-config-standard",
+  "plugins": [
+    "stylelint-order"
+  ],
+  "rules": {
+    "no-descending-specificity": null,
+    "order/properties-alphabetical-order": true
+  }
+}

postcss.config.js

@@ -12,7 +12,8 @@ module.exports = {
     'postcss-header': {
       header: rollupConfig.output[0].banner,
     },
-    autoprefixer: {},
-    stylefmt: {},
+    stylelint: {
+      fix: true,
+    },
   },
 };