fix plugins

Author: vasia

package.json

@@ -46,7 +46,7 @@
     "jade": "^1.11.0",
     "jest": "^20.0.4",
     "node-sass": "^4.10.0",
-    "postcss-custom-properties": "^9.0.2",
+    "postcss-css-variables": "^0.13.0",
     "pug": "^2.0.0-rc.3",
     "stylus": "^0.54.5",
     "typescript": "^2.5.2",

postcss.config.js

@@ -1,6 +1,6 @@
 module.exports = {
   plugins: {
-    'postcss-custom-properties': {},
+    'postcss-css-variables': {},
     'postcss-nested': {}
   }
 }