fix: make custom selectors work again

Author: buschtoens

lib/clark-plugin.js

@@ -24,6 +24,10 @@ module.exports = class ClarkPlugin extends Plugin {
       // Use :enter, which is equal to :hover and :focus combined
       require('postcss-pseudo-class-enter'),
 
+      // https://github.com/postcss/postcss-custom-selectorsx
+      // @custom-selector :--heading h1, h2, h3;
+      require('postcss-custom-selectors'),
+
       // https://github.com/jedmao/postcss-nested-props
       // Nest properties like `font: { size: 10px; family: Helvetica; }`
       // @TODO: https://github.com/jedmao/postcss-nested-props/issues/9
@@ -91,7 +95,6 @@ module.exports = class ClarkPlugin extends Plugin {
 
         // Explicitly enable features that we want, despite being proposals yet.
         features: {
-          'custom-selectors': true,
           'custom-properties': true,
           'custom-media-queries': true,
           'nesting-rules': true,

package.json

@@ -22,6 +22,7 @@
     "postcss-calc": "^7.0.1",
     "postcss-color-function": "^4.1.0",
     "postcss-conditionals": "^2.1.0",
+    "postcss-custom-selectors": "^5.1.2",
     "postcss-each": "^0.10.0",
     "postcss-easing-gradients": "^3.0.1",
     "postcss-for": "^2.1.1",