Push custom-options

public/theme-engine.js

@@ -0,0 +1,14 @@
+/**
+ * Passes a message through to the React backend.
+ * @param type The message type.
+ * @param data The message data.
+ */
+function passthrough(type, data) {
+  document.dispatchEvent(new CustomEvent('domMessage', {
+    type, msg: data
+  }))
+}
+
+function setConfigValue(key, value) {
+  passthrough('updateConfig', {setting: key, value})
+}