fix: transpile not, matches, has & custom selectors

These are notsupported on outdated Android emulator browsers.

lib/clark-plugin.js

@@ -79,7 +79,7 @@ module.exports = class ClarkPlugin extends Plugin {
         browsers: this.browsers,
 
         // https://cssdb.org/
-        stage: 4,
+        stage: 3,
 
         // Disable `preserve` so that the resulting CSS is consistent among all
         // browsers, diminishing the probability of discovering bugs only when
@@ -91,7 +91,16 @@ module.exports = class ClarkPlugin extends Plugin {
           'custom-properties': true,
           'custom-media-queries': true,
           'nesting-rules': true,
-          'pseudo-class-any-link': true
+          'pseudo-class-any-link': true,
+
+          // These are mostly due to terribly outdated Chrome versions in the
+          // Android emulator or super-low-end devices.
+          // @TODO Remove or `preserve`, once Android emulators caught up.
+          'not-pseudo-class': true,
+          'matches-pseudo-class': true,
+          'has-pseudo-class': true,
+
+          'custom-selectors': true
         },
 
         autoprefixer: {