Upgrade stylelint and improve the way we run it (#440)

This turns off the ignore for SCSS module files and makes stylelint use `.gitignore`. This is the same way we ignore files for ESLint.

package.json

@@ -14,7 +14,7 @@
         "test:prettier": "./scripts/test-prettier.sh",
         "test:lint": "yarn test:lint:md && yarn test:lint:css && yarn test:lint:js",
         "test:lint:md": "remark \"packages/*/CHANGELOG.md\" --frail --quiet",
-        "test:lint:css": "stylelint --ignore-pattern **/*.module.scss **/*.scss",
+        "test:lint:css": "stylelint \"**/*.scss\" \"**/*.css\" --ignore-path .gitignore",
         "test:lint:js": "eslint . --ignore-path .gitignore --ext .jsx --ext .js"
     },
     "devDependencies": {
@@ -55,10 +55,10 @@
         "react": "^16.8.6",
         "react-dom": "^16.8.6",
         "remark-cli": "^5.0.0",
-        "stylelint": "^9.10.1",
-        "stylelint-config-prettier": "^4.0.0",
-        "stylelint-config-recommended-scss": "^3.2.0",
-        "stylelint-scss": "^3.5.0"
+        "stylelint": "^10.1.0",
+        "stylelint-config-prettier": "^5.2.0",
+        "stylelint-config-recommended-scss": "^3.3.0",
+        "stylelint-scss": "^3.10.0"
     },
     "repository": {
         "type": "git",

stylelint.config.js

@@ -4,5 +4,13 @@ module.exports = {
         // Turned off due to false positives:
         // https://github.com/stylelint/stylelint/issues/2489
         'no-descending-specificity': null,
+        // `:global` is used for CSS modules
+        // https://github.com/stylelint/stylelint/issues/2208#issuecomment-269245751
+        'selector-pseudo-class-no-unknown': [
+            true,
+            {
+                ignorePseudoClasses: ['global'],
+            },
+        ],
     },
 };