added hex code form

mobile_facets.routing.yml

@@ -0,0 +1,7 @@
+mobile_facets.settings:
+  path: '/admin/config/mobile_facets/settings'
+  defaults:
+    _form: '\Drupal\mobile_facets\Form\SettingsForm'
+    _title: 'Mobile Facets Settings'
+  requirements:
+    _permission: 'administer site configuration'

src/Form/SettingsForm.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace Drupal\mobile_facets\Form;
+
+use Drupal\Core\Form\ConfigFormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Configure Mobile Facets settings.
+ */
+class SettingsForm extends ConfigFormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEditableConfigNames() {
+    return ['mobile_facets.settings'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'mobile_facets_settings_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    $config = $this->config('mobile_facets.settings');
+
+    $form['color'] = [
+      '#type' => 'color',
+      '#title' => $this->t('Custom Color'),
+      '#default_value' => $config->get('color') ?? '#000000', // Default to black if not set.
+      '#description' => $this->t('Enter a hex color code for your module (e.g., #FF0000 for red).'),
+    ];
+
+    return parent::buildForm($form, $form_state);
+  }
+
+}