diff --git a/package-lock.json b/package-lock.json
index 3e0c497..e7c6a72 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -73,12 +73,13 @@
       }
     },
     "@alexlit/config-stylelint": {
-      "version": "0.3.3",
-      "resolved": "https://registry.npmjs.org/@alexlit/config-stylelint/-/config-stylelint-0.3.3.tgz",
-      "integrity": "sha512-BV3Og9PV+U8dBXsdhEBMeN43v8/hZxmGZfaXgBeBQNp+GULu3awLHAL1z3m4lRRhVRxGnaRInsdgs8wlnmLA0w==",
+      "version": "0.4.0",
+      "resolved": "https://registry.npmjs.org/@alexlit/config-stylelint/-/config-stylelint-0.4.0.tgz",
+      "integrity": "sha512-SN2e9BRUpKoKlt3Z5VFK0ybdiSWlV7ZU2s0PTPAcWd+fwprx0foZOy6BmcmPMdStIgYGsk/1+B3UIB+dLPWAJQ==",
       "dev": true,
       "requires": {
         "stylelint": "^13.9.0",
+        "stylelint-a11y": "^1.2.3",
         "stylelint-config-idiomatic-order": "^8.1.0",
         "stylelint-config-prettier": "^8.0.2",
         "stylelint-config-standard": "^20.0.0",
@@ -89,16 +90,16 @@
       }
     },
     "@alexlit/lint-kit": {
-      "version": "0.18.1",
-      "resolved": "https://registry.npmjs.org/@alexlit/lint-kit/-/lint-kit-0.18.1.tgz",
-      "integrity": "sha512-JJWUn9FAdo/HIubGIEcnJtHfwL8sSgbQyAOVIeuhfNBBmo5lQ9QF4cqielwII/W79GhoVVHhd/eONPh0p1alew==",
+      "version": "0.19.0",
+      "resolved": "https://registry.npmjs.org/@alexlit/lint-kit/-/lint-kit-0.19.0.tgz",
+      "integrity": "sha512-oYoc/8sesRJoFCCkliGeVQy+y0hRJSXwQqKYcTfIpNa37tUZL7yKXqWfqyi4t91+8Puje5dYiBqVUslIFSJFhw==",
       "dev": true,
       "requires": {
         "@alexlit/config-commitlint": "^0.0.4",
         "@alexlit/config-eslint": "^0.14.1",
         "@alexlit/config-markdownlint": "0.2.2",
         "@alexlit/config-prettier": "^0.3.1",
-        "@alexlit/config-stylelint": "^0.3.3",
+        "@alexlit/config-stylelint": "^0.4.0",
         "husky": "^4.3.8",
         "lint-staged": "^10.5.3"
       }
@@ -271,9 +272,9 @@
       "integrity": "sha512-N3UxG+uuF4CMYoNj8AhnbAcJF0PiuJ9KHuy1lQmkYsxTer/MAH9UBNHsBoAX/4s6NvlDD047No8mYVGGzLL4hg=="
     },
     "@babel/runtime": {
-      "version": "7.12.5",
-      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.12.5.tgz",
-      "integrity": "sha512-plcc+hbExy3McchJCEQG3knOsuh3HH+Prx1P6cLIkET/0dLuQDEnrT+s27Axgc9bqfsmNUNHfscgMUdBpC9xfg==",
+      "version": "7.12.13",
+      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.12.13.tgz",
+      "integrity": "sha512-8+3UMPBrjFa/6TtKi/7sehPKqfAm4g6K+YQjyyFOLUTxzOngcRZTlAVY8sc2CORJYqdHQY8gRPHmn+qo15rCBw==",
       "dev": true,
       "requires": {
         "regenerator-runtime": "^0.13.4"
@@ -679,9 +680,9 @@
       }
     },
     "@prettier/plugin-ruby": {
-      "version": "1.5.1",
-      "resolved": "https://registry.npmjs.org/@prettier/plugin-ruby/-/plugin-ruby-1.5.1.tgz",
-      "integrity": "sha512-bOFNRk1XK29PABZfX9oxnmMa2YeuDKb3Rwg6QK+FIZZOjqdUWn7F3wm3WRD05F+ALBzEJCC6Q62vxv917SHp0Q==",
+      "version": "1.5.2",
+      "resolved": "https://registry.npmjs.org/@prettier/plugin-ruby/-/plugin-ruby-1.5.2.tgz",
+      "integrity": "sha512-hHX9ooxGQ4PC4FHge6HmK8LLUhLCu3lk1fVt0TJXvV5AlnY47PaBpQgQ58BzyrU9/EfZj3rpcIKiQQdelkvWNA==",
       "dev": true,
       "requires": {
         "prettier": ">=1.10"
@@ -1037,9 +1038,9 @@
       "integrity": "sha512-Z7tMw1ytTXt5jqMcOP+OQteU1VuNK9Y02uuJtKQ1Sv69jXQKKg5cibLwGJow8yzZP+eAc18EmLGPal0bp36rvQ=="
     },
     "astring": {
-      "version": "1.6.0",
-      "resolved": "https://registry.npmjs.org/astring/-/astring-1.6.0.tgz",
-      "integrity": "sha512-8Rhu9cQMu4CSie4IOTAgQl75kZ8dp+gmOipjCAkV1ZVSwuDXRKXDbi8YAlCOKzIh3mws/hNoXJu8EkZwfCakLQ==",
+      "version": "1.6.2",
+      "resolved": "https://registry.npmjs.org/astring/-/astring-1.6.2.tgz",
+      "integrity": "sha512-STGFbQN/qccrGAxqsnFkqAeVNTCvgN5uiD+vd75DNDvsoYZkDtYwW1rZvM/8xY1lMtOfisqh+MBU4ilsbLhd2g==",
       "dev": true
     },
     "at-least-node": {
@@ -3160,9 +3161,9 @@
       "dev": true
     },
     "get-intrinsic": {
-      "version": "1.1.0",
-      "resolved": "https://registry.npmjs.org/get-intrinsic/-/get-intrinsic-1.1.0.tgz",
-      "integrity": "sha512-M11rgtQp5GZMZzDL7jLTNxbDfurpzuau5uqRWDPvlHjfvg3TdScAZo96GLvhMjImrmR8uAt0FS2RLoMrfWGKlg==",
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/get-intrinsic/-/get-intrinsic-1.1.1.tgz",
+      "integrity": "sha512-kWZrnVM42QCiEA2Ig1bG8zjoIMOgxWwYCEeNdwY6Tv/cOSeGpcoX4pXHfKUxNKVoArnrEr2e9srnAxxGIraS9Q==",
       "dev": true,
       "requires": {
         "function-bind": "^1.1.1",
diff --git a/package.json b/package.json
index f2aefee..7dbf081 100644
--- a/package.json
+++ b/package.json
@@ -47,6 +47,6 @@
     "stylelint-use-nesting": "^3.0.0"
   },
   "devDependencies": {
-    "@alexlit/lint-kit": "0.18.1"
+    "@alexlit/lint-kit": "0.19.0"
   }
 }
diff --git a/plugins/scss.js b/plugins/scss.js
index 1f8f1b3..9481465 100644
--- a/plugins/scss.js
+++ b/plugins/scss.js
@@ -2,6 +2,7 @@ module.exports = {
   plugins: ['stylelint-scss'],
 
   rules: {
+    'scss/at-extend-no-missing-placeholder': true,
     'scss/at-rule-no-unknown': [
       true,
       {
diff --git a/test/scss.scss b/test/scss.scss
index 84a1388..cb09b2b 100644
--- a/test/scss.scss
+++ b/test/scss.scss
@@ -24,6 +24,7 @@
   }
 }
 
+%sdf,
 .sdf {
   animation-name: skew;
 
@@ -39,6 +40,8 @@ a {
 }
 
 .ui-button {
+  @extend %sdf;
+
   @include variables;
 
   position: relative;