diff --git a/claro.info.yml b/claro.info.yml
index 40341b1..c653077 100644
--- a/claro.info.yml
+++ b/claro.info.yml
@@ -49,7 +49,6 @@ libraries-override:
     css:
       component:
         /core/themes/stable/css/core/vertical-tabs.css: false
-
     js:
       misc/vertical-tabs.js: js/claro.vertical-tabs.js
 
diff --git a/claro.libraries.yml b/claro.libraries.yml
index 5a026e0..46c427e 100644
--- a/claro.libraries.yml
+++ b/claro.libraries.yml
@@ -226,18 +226,5 @@ vertical-tabs:
   css:
     component:
       css/dist/components/vertical-tabs.css: {}
-  drupalSettings:
-    verticalTabs:
-      paneClasses: []
-      paneClassesFirst:
-        - vertical-tabs__item--first
-      paneClassesLast:
-        - vertical-tabs__item--last
-      paneClassesHidden:
-        - vertical-tab--hidden
-      paneWrapperClasses:
-        - vertical-tabs__items--processed
-      menuItemClassesHidden:
-        - vertical-tabs__menu-item--hidden
   dependencies:
     - claro/global-styling
diff --git a/js/claro.vertical-tabs.es6.js b/js/claro.vertical-tabs.es6.js
index 523e3ff..01029d8 100644
--- a/js/claro.vertical-tabs.es6.js
+++ b/js/claro.vertical-tabs.es6.js
@@ -47,17 +47,7 @@
    *   Attaches behaviors for vertical tabs.
    */
   Drupal.behaviors.claroVerticalTabs = {
-    attach(context, settings) {
-      const verticalTabsDefaults = {
-        paneClasses: ['vertical-tabs__pane'],
-        paneClassesFirst: ['first'],
-        paneClassesLast: ['last'],
-        paneClassesHidden: ['vertical-tab--hidden'],
-        paneWrapperClasses: ['vertical-tabs__panes'],
-        menuItemClassesHidden: [],
-      };
-      const verticalTabsSettings = $.extend({}, verticalTabsDefaults, settings.verticalTabs || {});
-
+    attach(context) {
       /**
        * Binds a listener to handle fragment link clicks and URL hash changes.
        */
@@ -72,7 +62,7 @@
         .find('[data-vertical-tabs-panes]')
         .once('vertical-tabs')
         .each(function initializeVerticalTabs() {
-          const $this = $(this).addClass(verticalTabsSettings.paneWrapperClasses.join(' '));
+          const $this = $(this).addClass('vertical-tabs__items--processed');
           const focusID = $this.find(':hidden.vertical-tabs__active-tab').val();
           let tabFocus;
 
@@ -96,7 +86,6 @@
             const verticalTab = new Drupal.verticalTab({
               title: $that.find('> summary').text(),
               details: $that,
-              settings: verticalTabsSettings,
             });
             /* eslint-enable new-cap */
             tabList.append(verticalTab.item);
@@ -104,7 +93,6 @@
               // prop() can't be used on browsers not supporting details
               // element, the style won't apply to them if prop() is used.
               .removeAttr('open')
-              .addClass(verticalTabsSettings.paneClasses.join(' '))
               .addClass('js-vertical-tabs-pane')
               .data('verticalTab', verticalTab);
             if (this.id === focusID) {
@@ -144,8 +132,6 @@
    *   The name of the tab.
    * @param {jQuery} settings.details
    *   The jQuery object of the details element that is the tab pane.
-   * @param {jQuery} settings.settings
-   *   The jQuery object of vertical tab settings.
    *
    * @fires event:summaryUpdated
    *
@@ -153,7 +139,6 @@
    */
   Drupal.verticalTab = function verticalTab(settings) {
     const self = this;
-    this.settings = settings.settings;
     $.extend(this, settings, Drupal.theme('verticalTab', settings));
 
     this.item.addClass('js-vertical-tabs-menu-item');
@@ -274,30 +259,28 @@
     tabShow() {
       // Display the tab.
       this.item
-        .removeClass(this.settings.menuItemClassesHidden.join(' '))
+        .removeClass('vertical-tabs__menu-item--hidden')
         .show();
       // Show the vertical tabs.
       this.item.closest('.js-form-type-vertical-tabs').show();
       // Display the details element.
       this.details
-        .removeClass(this.settings.paneClassesHidden.join(' '))
-        .removeClass('js-vertical-tab-hidden')
+        .removeClass('vertical-tab--hidden js-vertical-tab-hidden')
         .show();
       // Update first and last CSS classes for details.
       this.details
         .parent()
         .children('.js-vertical-tabs-pane')
-        .removeClass(this.settings.paneClassesFirst.join(' '))
-        .removeClass(this.settings.paneClassesLast.join(' '))
+        .removeClass('vertical-tabs__item--first vertical-tabs__item--last')
         .filter(':visible')
         .eq(0)
-        .addClass(this.settings.paneClassesFirst.join(' '));
+        .addClass('vertical-tabs__item--first');
       this.details
         .parent()
         .children('.js-vertical-tabs-pane')
         .filter(':visible')
         .eq(-1)
-        .addClass(this.settings.paneClassesLast.join(' '));
+        .addClass('vertical-tabs__item--last');
       // Make tab active, but without triggering focus.
       this.focus(false);
       return this;
@@ -312,28 +295,26 @@
     tabHide() {
       // Hide this tab.
       this.item
-        .addClass(this.settings.menuItemClassesHidden.join(' '))
+        .addClass('vertical-tabs__menu-item--hidden')
         .hide();
       // Hide the details element.
       this.details
-        .addClass(this.settings.paneClassesHidden.join(' '))
-        .addClass('js-vertical-tab-hidden')
+        .addClass('vertical-tab--hidden js-vertical-tab-hidden')
         .hide();
       // Update first and last CSS classes for details.
       this.details
         .parent()
         .children('.js-vertical-tabs-pane')
-        .removeClass(this.settings.paneClassesFirst.join(' '))
-        .removeClass(this.settings.paneClassesLast.join(' '))
+        .removeClass('vertical-tabs__item--first vertical-tabs__item--last')
         .filter(':visible')
         .eq(0)
-        .addClass(this.settings.paneClassesFirst.join(' '));
+        .addClass('vertical-tabs__item--first');
       this.details
         .parent()
         .children('.js-vertical-tabs-pane')
         .filter(':visible')
         .eq(-1)
-        .addClass(this.settings.paneClassesLast.join(' '));
+        .addClass('vertical-tabs__item--last');
       // Focus the first visible tab (if there is one).
       const $firstTab = this.details
         .siblings('.js-vertical-tabs-pane:not(.js-vertical-tab-hidden)')
diff --git a/js/claro.vertical-tabs.js b/js/claro.vertical-tabs.js
index 0582a5c..9a21bd3 100644
--- a/js/claro.vertical-tabs.js
+++ b/js/claro.vertical-tabs.js
@@ -13,21 +13,11 @@
   };
 
   Drupal.behaviors.claroVerticalTabs = {
-    attach: function attach(context, settings) {
-      var verticalTabsDefaults = {
-        paneClasses: ['vertical-tabs__pane'],
-        paneClassesFirst: ['first'],
-        paneClassesLast: ['last'],
-        paneClassesHidden: ['vertical-tab--hidden'],
-        paneWrapperClasses: ['vertical-tabs__panes'],
-        menuItemClassesHidden: []
-      };
-      var verticalTabsSettings = $.extend({}, verticalTabsDefaults, settings.verticalTabs || {});
-
+    attach: function attach(context) {
       $('body').once('vertical-tabs-fragments').on('formFragmentLinkClickOrHashChange.verticalTabs', handleFragmentLinkClickOrHashChange);
 
       $(context).find('[data-vertical-tabs-panes]').once('vertical-tabs').each(function initializeVerticalTabs() {
-        var $this = $(this).addClass(verticalTabsSettings.paneWrapperClasses.join(' '));
+        var $this = $(this).addClass('vertical-tabs__items--processed');
         var focusID = $this.find(':hidden.vertical-tabs__active-tab').val();
         var tabFocus = void 0;
 
@@ -44,12 +34,11 @@
 
           var verticalTab = new Drupal.verticalTab({
             title: $that.find('> summary').text(),
-            details: $that,
-            settings: verticalTabsSettings
+            details: $that
           });
 
           tabList.append(verticalTab.item);
-          $that.removeAttr('open').addClass(verticalTabsSettings.paneClasses.join(' ')).addClass('js-vertical-tabs-pane').data('verticalTab', verticalTab);
+          $that.removeAttr('open').addClass('js-vertical-tabs-pane').data('verticalTab', verticalTab);
           if (this.id === focusID) {
             tabFocus = $that;
           }
@@ -72,7 +61,6 @@
 
   Drupal.verticalTab = function verticalTab(settings) {
     var self = this;
-    this.settings = settings.settings;
     $.extend(this, settings, Drupal.theme('verticalTab', settings));
 
     this.item.addClass('js-vertical-tabs-menu-item');
@@ -154,25 +142,25 @@
       this.summary.html(summary);
     },
     tabShow: function tabShow() {
-      this.item.removeClass(this.settings.menuItemClassesHidden.join(' ')).show();
+      this.item.removeClass('vertical-tabs__menu-item--hidden').show();
 
       this.item.closest('.js-form-type-vertical-tabs').show();
 
-      this.details.removeClass(this.settings.paneClassesHidden.join(' ')).removeClass('js-vertical-tab-hidden').show();
+      this.details.removeClass('vertical-tab--hidden js-vertical-tab-hidden').show();
 
-      this.details.parent().children('.js-vertical-tabs-pane').removeClass(this.settings.paneClassesFirst.join(' ')).removeClass(this.settings.paneClassesLast.join(' ')).filter(':visible').eq(0).addClass(this.settings.paneClassesFirst.join(' '));
-      this.details.parent().children('.js-vertical-tabs-pane').filter(':visible').eq(-1).addClass(this.settings.paneClassesLast.join(' '));
+      this.details.parent().children('.js-vertical-tabs-pane').removeClass('vertical-tabs__item--first vertical-tabs__item--last').filter(':visible').eq(0).addClass('vertical-tabs__item--first');
+      this.details.parent().children('.js-vertical-tabs-pane').filter(':visible').eq(-1).addClass('vertical-tabs__item--last');
 
       this.focus(false);
       return this;
     },
     tabHide: function tabHide() {
-      this.item.addClass(this.settings.menuItemClassesHidden.join(' ')).hide();
+      this.item.addClass('vertical-tabs__menu-item--hidden').hide();
 
-      this.details.addClass(this.settings.paneClassesHidden.join(' ')).addClass('js-vertical-tab-hidden').hide();
+      this.details.addClass('vertical-tab--hidden js-vertical-tab-hidden').hide();
 
-      this.details.parent().children('.js-vertical-tabs-pane').removeClass(this.settings.paneClassesFirst.join(' ')).removeClass(this.settings.paneClassesLast.join(' ')).filter(':visible').eq(0).addClass(this.settings.paneClassesFirst.join(' '));
-      this.details.parent().children('.js-vertical-tabs-pane').filter(':visible').eq(-1).addClass(this.settings.paneClassesLast.join(' '));
+      this.details.parent().children('.js-vertical-tabs-pane').removeClass('vertical-tabs__item--first vertical-tabs__item--last').filter(':visible').eq(0).addClass('vertical-tabs__item--first');
+      this.details.parent().children('.js-vertical-tabs-pane').filter(':visible').eq(-1).addClass('vertical-tabs__item--last');
 
       var $firstTab = this.details.siblings('.js-vertical-tabs-pane:not(.js-vertical-tab-hidden)').eq(0);
       if ($firstTab.length) {