Revert

tests/dummy/app/controllers/application.ts

@@ -0,0 +1,15 @@
+import Controller from '@ember/controller';
+import { tracked } from '@glimmer/tracking';
+
+import type { Theme } from '@trusted-american/design-system/helpers/theme';
+
+export default class ApplicationController extends Controller {
+  @tracked theme: Theme = 'light';
+
+  get isDarkTheme(): boolean {
+    return this.theme === 'dark';
+  }
+  set isDarkTheme(value: boolean) {
+    this.theme = value ? 'dark' : 'light';
+  }
+}

tests/dummy/app/controllers/helpers.ts

@@ -1,9 +1,11 @@
 import Controller from '@ember/controller';
 import { tracked } from '@glimmer/tracking';
+
 import type { Theme } from '@trusted-american/design-system/helpers/theme';
 
 export default class HelpersController extends Controller {
   date = new Date();
+
   @tracked theme: Theme = 'light';
 
   get isDarkTheme(): boolean {

tests/dummy/app/templates/application.hbs

@@ -70,6 +70,13 @@
     />
   </:default>
   <:footer>
+    <Form::Check
+      @value={{this.isDarkTheme}}
+      @label="Dark theme"
+      @identifier="isDarkTheme"
+      @isSwitch={{true}}
+      @onChange={{fn (mut this.isDarkTheme)}}
+    />
   </:footer>
 </Aside>