diff --git a/core/misc/collapse.es6.js b/core/misc/collapse.es6.js
index 52fd244..022014a 100644
--- a/core/misc/collapse.es6.js
+++ b/core/misc/collapse.es6.js
@@ -9,12 +9,18 @@
    *
    * @constructor Drupal.CollapsibleDetails
    *
-   * @param {HTMLElement} node
-   *   The details element.
+   * @param {HTMLDetailsElement} node
+   *   The `<details>` tag to process.
    */
   function CollapsibleDetails(node) {
     this.$node = $(node);
-    this.$node.data('details', this);
+    // Details tag polyfill.
+    if (!Modernizr.details) {
+      this.$node.addClass('collapse-processed');
+      // Initialize and setup the legend, replicate summary tag functionality.
+      this.setupLegend();
+    }
+
     // Expand details if there are errors inside, or if it contains an
     // element that is targeted by the URI fragment identifier.
     const anchor =
@@ -39,7 +45,7 @@
        * @type {Array.<Drupal.CollapsibleDetails>}
        */
       instances: [],
-    },
+    }
   );
 
   $.extend(
@@ -55,11 +61,23 @@
       setupSummary() {
         this.$summary = $('<span class="summary"></span>');
         this.$node
-          .on('summaryUpdated', $.proxy(this.onSummaryUpdated, this))
+          .find('> summary')
+          .append(this.$summary);
+
+        this.$node
+          .on('summaryUpdated', this.onSummaryUpdated.bind(this))
           .trigger('summaryUpdated');
       },
 
       /**
+       * Update summary.
+       */
+      onSummaryUpdated: function () {
+        var text = $.trim(this.$node.drupalGetSummary());
+        this.$summary.html(text ? ' (' + text + ')' : '');
+      },
+
+      /**
        * Initialize and setup legend markup.
        */
       setupLegend() {
@@ -77,16 +95,14 @@
           .prepend($legend.contents())
           .appendTo($legend);
 
-        $legend
-          .append(this.$summary)
-          .on('click', $.proxy(this.onLegendClick, this));
+        $legend.on('click', this.onLegendClick.bind(this));
       },
 
       /**
        * Handle legend clicks.
        *
        * @param {jQuery.Event} e
-       *   The event triggered.
+       * jQuery Event object.
        */
       onLegendClick(e) {
         this.toggle();
@@ -94,24 +110,15 @@
       },
 
       /**
-       * Update summary.
-       */
-      onSummaryUpdated() {
-        const text = $.trim(this.$node.drupalGetSummary());
-        this.$summary.html(text ? ` (${text})` : '');
-      },
-
-      /**
-       * Toggle the visibility of a details element using smooth animations.
+       * Toggle the value of the open attribute.
        */
       toggle() {
         const isOpen = !!this.$node.attr('open');
-        const $summaryPrefix = this.$node.find(
-          '> summary span.details-summary-prefix',
-        );
+        const $summaryPrefix = this.$node.find('> summary span.details-summary-prefix');
         if (isOpen) {
           $summaryPrefix.html(Drupal.t('Show'));
-        } else {
+        }
+        else {
           $summaryPrefix.html(Drupal.t('Hide'));
         }
         // Delay setting the attribute to emulate chrome behavior and make
@@ -132,14 +139,10 @@
    *   Attaches behavior for the details element.
    */
   Drupal.behaviors.collapse = {
-    attach(context) {
-      if (Modernizr.details) {
-        return;
-      }
-      const $collapsibleDetails = $(context)
+    attach: function (context) {
+      var $collapsibleDetails = $(context)
         .find('details')
-        .once('collapse')
-        .addClass('collapse-processed');
+        .once('collapse');
       if ($collapsibleDetails.length) {
         for (let i = 0; i < $collapsibleDetails.length; i++) {
           CollapsibleDetails.instances.push(
diff --git a/core/misc/collapse.js b/core/misc/collapse.js
index bf312b9..f5693a5 100644
--- a/core/misc/collapse.js
+++ b/core/misc/collapse.js
@@ -8,7 +8,12 @@
 (function ($, Modernizr, Drupal) {
   function CollapsibleDetails(node) {
     this.$node = $(node);
-    this.$node.data('details', this);
+
+    if (!Modernizr.details) {
+      this.$node.addClass('collapse-processed');
+
+      this.setupLegend();
+    }
     var anchor = window.location.hash && window.location.hash !== '#' ? ", ".concat(window.location.hash) : '';
 
     if (this.$node.find(".error".concat(anchor)).length) {
@@ -16,7 +21,6 @@
     }
 
     this.setupSummary();
-    this.setupLegend();
   }
 
   $.extend(CollapsibleDetails, {
@@ -25,22 +29,27 @@
   $.extend(CollapsibleDetails.prototype, {
     setupSummary: function setupSummary() {
       this.$summary = $('<span class="summary"></span>');
-      this.$node.on('summaryUpdated', $.proxy(this.onSummaryUpdated, this)).trigger('summaryUpdated');
+
+      this.$node.find('> summary').append(this.$summary);
+
+      this.$node.on('summaryUpdated', this.onSummaryUpdated.bind(this)).trigger('summaryUpdated');
     },
+
+    onSummaryUpdated: function onSummaryUpdated() {
+      var text = $.trim(this.$node.drupalGetSummary());
+      this.$summary.html(text ? ' (' + text + ')' : '');
+    },
+
     setupLegend: function setupLegend() {
       var $legend = this.$node.find('> summary');
       $('<span class="details-summary-prefix visually-hidden"></span>').append(this.$node.attr('open') ? Drupal.t('Hide') : Drupal.t('Show')).prependTo($legend).after(document.createTextNode(' '));
       $('<a class="details-title"></a>').attr('href', "#".concat(this.$node.attr('id'))).prepend($legend.contents()).appendTo($legend);
-      $legend.append(this.$summary).on('click', $.proxy(this.onLegendClick, this));
+      $legend.on('click', this.onLegendClick.bind(this));
     },
     onLegendClick: function onLegendClick(e) {
       this.toggle();
       e.preventDefault();
     },
-    onSummaryUpdated: function onSummaryUpdated() {
-      var text = $.trim(this.$node.drupalGetSummary());
-      this.$summary.html(text ? " (".concat(text, ")") : '');
-    },
     toggle: function toggle() {
       var _this = this;
 
@@ -60,11 +69,7 @@
   });
   Drupal.behaviors.collapse = {
     attach: function attach(context) {
-      if (Modernizr.details) {
-        return;
-      }
-
-      var $collapsibleDetails = $(context).find('details').once('collapse').addClass('collapse-processed');
+      var $collapsibleDetails = $(context).find('details').once('collapse');
 
       if ($collapsibleDetails.length) {
         for (var i = 0; i < $collapsibleDetails.length; i++) {
diff --git a/core/modules/comment/comment-entity-form.es6.js b/core/modules/comment/comment-entity-form.es6.js
index 4f25c9b..a90a340 100644
--- a/core/modules/comment/comment-entity-form.es6.js
+++ b/core/modules/comment/comment-entity-form.es6.js
@@ -12,14 +12,14 @@
     attach(context) {
       const $context = $(context);
       $context
-        .find('fieldset.comment-entity-settings-form')
+        .find('.comment-node-settings-form')
         .drupalSetSummary(context =>
           Drupal.checkPlain(
             $(context)
-              .find('.js-form-item-comment input:checked')
+              .find('.js-form-item-comment-0-status input:checked')
               .next('label')
-              .text(),
-          ),
+              .text()
+          )
         );
     },
   };
diff --git a/core/modules/comment/comment-entity-form.js b/core/modules/comment/comment-entity-form.js
index 15196ca..420da34 100644
--- a/core/modules/comment/comment-entity-form.js
+++ b/core/modules/comment/comment-entity-form.js
@@ -9,8 +9,8 @@
   Drupal.behaviors.commentFieldsetSummaries = {
     attach: function attach(context) {
       var $context = $(context);
-      $context.find('fieldset.comment-entity-settings-form').drupalSetSummary(function (context) {
-        return Drupal.checkPlain($(context).find('.js-form-item-comment input:checked').next('label').text());
+      $context.find('.comment-node-settings-form').drupalSetSummary(function (context) {
+        return Drupal.checkPlain($(context).find('.js-form-item-comment-0-status input:checked').next('label').text());
       });
     }
   };
diff --git a/core/profiles/demo_umami/themes/umami/css/classy/components/collapse-processed.css b/core/profiles/demo_umami/themes/umami/css/classy/components/collapse-processed.css
index 1612930..40a326f 100644
--- a/core/profiles/demo_umami/themes/umami/css/classy/components/collapse-processed.css
+++ b/core/profiles/demo_umami/themes/umami/css/classy/components/collapse-processed.css
@@ -30,3 +30,6 @@
   transform: rotate(90deg);
   background-position: 75% 35%;
 }
+.collapse-processed .details-title {
+  color: #333;
+}
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php b/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php
index f760cf9..9de5bb7 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/ConfirmClassyCopiesTest.php
@@ -681,7 +681,7 @@ protected function getClassyHash($type, $file) {
         'book-navigation.css' => 'e8219368d360bd4a10763610ada85a1c',
         'breadcrumb.css' => '14268f8071dffd40ce7a39862b8fbc56',
         'button.css' => '3abebf58e144fd4150d80facdbe5d10f',
-        'collapse-processed.css' => 'e928df55485662a4499c9ba12def22e6',
+        'collapse-processed.css' => 'a37822b887d80917ba465cb8b9bbee60',
         'container-inline.css' => 'ae9caee6071b319ac97bf0bb3e14b542',
         'details.css' => 'fdd0606ea856072f5e6a19ab1a2e850e',
         'dialog.css' => 'f30e4423380f5f01d02ef0a93e010c53',
diff --git a/core/themes/bartik/css/classy/components/collapse-processed.css b/core/themes/bartik/css/classy/components/collapse-processed.css
index c8c7868..a4d3cbb 100644
--- a/core/themes/bartik/css/classy/components/collapse-processed.css
+++ b/core/themes/bartik/css/classy/components/collapse-processed.css
@@ -30,3 +30,6 @@
   transform: rotate(90deg);
   background-position: 75% 35%;
 }
+.collapse-processed .details-title {
+  color: #333;
+}
diff --git a/core/themes/classy/css/components/collapse-processed.css b/core/themes/classy/css/components/collapse-processed.css
index e9206ac..3d6002a 100644
--- a/core/themes/classy/css/components/collapse-processed.css
+++ b/core/themes/classy/css/components/collapse-processed.css
@@ -30,3 +30,6 @@
   transform: rotate(90deg);
   background-position: 75% 35%;
 }
+.collapse-processed .details-title {
+  color: #333;
+}
diff --git a/core/themes/seven/css/classy/components/collapse-processed.css b/core/themes/seven/css/classy/components/collapse-processed.css
index c8c7868..a4d3cbb 100644
--- a/core/themes/seven/css/classy/components/collapse-processed.css
+++ b/core/themes/seven/css/classy/components/collapse-processed.css
@@ -30,3 +30,6 @@
   transform: rotate(90deg);
   background-position: 75% 35%;
 }
+.collapse-processed .details-title {
+  color: #333;
+}
diff --git a/core/themes/seven/css/components/entity-meta.css b/core/themes/seven/css/components/entity-meta.css
index cf614fd..133021f 100644
--- a/core/themes/seven/css/components/entity-meta.css
+++ b/core/themes/seven/css/components/entity-meta.css
@@ -67,6 +67,8 @@
  * @todo Consider removing this after https://www.drupal.org/node/2493957 has
  *   been solved.
  */
-.entity-meta .seven-details .summary {
-  display: none;
+.entity-meta details .summary {
+  color: #666;
+  text-transform: none;
+  font-size: 0.85em;
 }