diff --git a/core/core.libraries.yml b/core/core.libraries.yml
index 85c956228e..a929536624 100644
--- a/core/core.libraries.yml
+++ b/core/core.libraries.yml
@@ -903,3 +903,31 @@ underscore:
     gpl-compatible: true
   js:
     assets/vendor/underscore/underscore-min.js: { weight: -20, minified: true }
+
+drupal.dialog.off_canvas:
+  version: VERSION
+  js:
+    misc/dialog/off-canvas.js: {}
+  css:
+    base:
+      misc/dialog/off-canvas.reset.css: {}
+      misc/dialog/off-canvas.base.css: {}
+      misc/dialog/off-canvas.css: {}
+      # Add group setting to make sure this CSS load before any jQuery UI Dialog
+      # CSS.
+      misc/dialog/off-canvas.theme.css: { group: 200 }
+    component:
+      misc/dialog/off-canvas.motion.css: {}
+      misc/dialog/off-canvas.button.css: {}
+      misc/dialog/off-canvas.form.css: {}
+      misc/dialog/off-canvas.table.css: {}
+      misc/dialog/off-canvas.details.css: {}
+      misc/dialog/off-canvas.tabledrag.css: {}
+      misc/dialog/off-canvas.dropbutton.css: {}
+  dependencies:
+    - core/jquery
+    - core/drupal
+    - core/drupal.ajax
+    - core/drupal.announce
+    - core/drupal.dialog
+    - core/drupal.dialog.ajax
diff --git a/core/core.services.yml b/core/core.services.yml
index 76088786cd..98996a6101 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1065,6 +1065,11 @@ services:
     arguments: ['@title_resolver']
     tags:
       - { name: render.main_content_renderer, format: drupal_dialog }
+  main_content_renderer.off_canvas:
+    class: Drupal\Core\Render\MainContent\OffCanvasRenderer
+    arguments: ['@title_resolver', '@renderer']
+    tags:
+      - { name: render.main_content_renderer, format: drupal_dialog.off_canvas }
   main_content_renderer.modal:
     class: Drupal\Core\Render\MainContent\ModalRenderer
     arguments: ['@title_resolver']
diff --git a/core/modules/outside_in/src/Ajax/OpenOffCanvasDialogCommand.php b/core/lib/Drupal/Core/Ajax/OpenOffCanvasDialogCommand.php
similarity index 96%
rename from core/modules/outside_in/src/Ajax/OpenOffCanvasDialogCommand.php
rename to core/lib/Drupal/Core/Ajax/OpenOffCanvasDialogCommand.php
index c5e2b2a5d1..da6a26e35a 100644
--- a/core/modules/outside_in/src/Ajax/OpenOffCanvasDialogCommand.php
+++ b/core/lib/Drupal/Core/Ajax/OpenOffCanvasDialogCommand.php
@@ -1,15 +1,11 @@
 <?php
 
-namespace Drupal\outside_in\Ajax;
-
-use Drupal\Core\Ajax\OpenDialogCommand;
+namespace Drupal\Core\Ajax;
 
 /**
  * Defines an AJAX command to open content in a dialog in a off-canvas dialog.
  *
  * @ingroup ajax
- *
- * @internal
  */
 class OpenOffCanvasDialogCommand extends OpenDialogCommand {
 
diff --git a/core/modules/outside_in/src/Render/MainContent/OffCanvasRenderer.php b/core/lib/Drupal/Core/Render/MainContent/OffCanvasRenderer.php
similarity index 89%
rename from core/modules/outside_in/src/Render/MainContent/OffCanvasRenderer.php
rename to core/lib/Drupal/Core/Render/MainContent/OffCanvasRenderer.php
index 8bcaa578d4..55bf8eb7d1 100644
--- a/core/modules/outside_in/src/Render/MainContent/OffCanvasRenderer.php
+++ b/core/lib/Drupal/Core/Render/MainContent/OffCanvasRenderer.php
@@ -1,13 +1,12 @@
 <?php
 
-namespace Drupal\outside_in\Render\MainContent;
+namespace Drupal\Core\Render\MainContent;
 
 use Drupal\Core\Ajax\AjaxResponse;
 use Drupal\Core\Controller\TitleResolverInterface;
-use Drupal\Core\Render\MainContent\DialogRenderer;
 use Drupal\Core\Render\RendererInterface;
 use Drupal\Core\Routing\RouteMatchInterface;
-use Drupal\outside_in\Ajax\OpenOffCanvasDialogCommand;
+use Drupal\Core\Ajax\OpenOffCanvasDialogCommand;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
@@ -47,7 +46,7 @@ public function renderResponse(array $main_content, Request $request, RouteMatch
     $content = $this->renderer->renderRoot($main_content);
     // Attach the library necessary for using the OpenOffCanvasDialogCommand and
     // set the attachments for this Ajax response.
-    $main_content['#attached']['library'][] = 'outside_in/drupal.off_canvas';
+    $main_content['#attached']['library'][] = 'core/drupal.dialog.off_canvas';
     $response->setAttachments($main_content['#attached']);
 
     // If the main content doesn't provide a title, use the title resolver.
diff --git a/core/modules/outside_in/css/off-canvas.base.css b/core/misc/dialog/off-canvas.base.css
similarity index 95%
rename from core/modules/outside_in/css/off-canvas.base.css
rename to core/misc/dialog/off-canvas.base.css
index 4263886b24..8747b286e7 100644
--- a/core/modules/outside_in/css/off-canvas.base.css
+++ b/core/misc/dialog/off-canvas.base.css
@@ -1,6 +1,6 @@
 /*
  * @file
- * Set base styles for the settings tray.
+ * Set base styles for the off-canvas dialog.
  */
 
 /* Set some global attributes. */
@@ -217,18 +217,18 @@
 }
 #drupal-off-canvas .messages--status {
   background-color: #f3faef;
-  background-image: url(../../../misc/icons/73b355/check.svg);
+  background-image: url(../icons/73b355/check.svg);
   color: #325e1c;
 }
 #drupal-off-canvas .messages--warning {
   background-color: #fdf8ed;
-  background-image: url(../../../misc/icons/e29700/warning.svg);
+  background-image: url(../icons/e29700/warning.svg);
   color: #734c00;
 }
 
 #drupal-off-canvas .messages--error {
   background-color: #fcf4f2;
-  background-image: url(../../../misc/icons/e32700/error.svg);
+  background-image: url(../icons/e32700/error.svg);
   color: #a51b00;
 }
 
diff --git a/core/misc/dialog/off-canvas.button.css b/core/misc/dialog/off-canvas.button.css
new file mode 100644
index 0000000000..e37b7ac4e0
--- /dev/null
+++ b/core/misc/dialog/off-canvas.button.css
@@ -0,0 +1,117 @@
+/**
+ * Visual styling for buttons in the off-canvas dialog.
+ *
+ * @see seven/css/components/buttons.css
+ */
+
+#drupal-off-canvas button,
+#drupal-off-canvas .button {
+  -webkit-appearance: none;
+  -moz-appearance: none;
+  margin: 0 0 10px;
+  padding: 0;
+  border: 0;
+  box-shadow: none;
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+  line-height: normal;
+  text-transform: none;
+  text-decoration: none;
+  cursor: pointer;
+}
+#drupal-off-canvas button.link {
+  display: inline;
+  background: transparent;
+  font-size: 14px;
+  color: #85bef4;
+  transition: color .5s ease;
+}
+#drupal-off-canvas button.link:hover,
+#drupal-off-canvas button.link:focus {
+  color: #46a0f5;
+  text-decoration: none;
+}
+#drupal-off-canvas input[type="submit"].button {
+  display: inline-block;
+  position: relative;
+  width: 100%;
+  height: auto;
+  padding: 4px 20px;
+  border: 0;
+  border-radius: 20em;
+  background: #777;
+  font-weight: 600;
+  font-size: 14px;
+  color: #f5f5f5;
+  text-align: center;
+  cursor: pointer;
+  transition: background .5s ease;
+}
+#drupal-off-canvas input[type="submit"].button:hover,
+#drupal-off-canvas input[type="submit"].button:focus,
+#drupal-off-canvas input[type="submit"].button:active {
+  border: 0;
+  color: #fff;
+  text-decoration: none;
+  outline: none;
+  z-index: 10;
+}
+#drupal-off-canvas input[type="submit"].button:focus,
+#drupal-off-canvas input[type="submit"].button:active {
+  box-shadow: 0 3px 3px 2px rgba(0,0,0,0.1);
+}
+#drupal-off-canvas input[type="submit"].button--primary {
+  border: 0;
+  background: #277abd;
+  color: #fff;
+  margin-top: 15px;
+}
+#drupal-off-canvas input[type="submit"].button--primary:hover,
+#drupal-off-canvas input[type="submit"].button--primary:focus,
+#drupal-off-canvas input[type="submit"].button--primary:active {
+  background: #2b8bd8;
+  outline: none;
+}
+#drupal-off-canvas .button-action:before {
+  margin-left: -0.2em; /* LTR */
+  padding-right: 0.2em; /* LTR */
+  font-size: 14px;
+  line-height: 16px;
+}
+[dir="rtl"] #drupal-off-canvas .button-action:before {
+  margin-right: -0.2em;
+  margin-left: 0;
+  padding-right: 0;
+  padding-left: 0.2em;
+}
+#drupal-off-canvas .no-touchevents .button--small {
+  font-size: 13px;
+  padding: 2px 1em;  /* 1 */
+}
+#drupal-off-canvas .button:disabled,
+#drupal-off-canvas .button:disabled:active,
+#drupal-off-canvas .button.is-disabled,
+#drupal-off-canvas .button.is-disabled:active {
+  border: 0;
+  background: #555;
+  color: #5c5c5c;
+  font-weight: normal;
+  cursor: default;
+}
+#drupal-off-canvas .button--danger {
+  border-radius: 0;
+  color: #c72100;
+  font-weight: 400;
+  text-decoration: none;
+}
+#drupal-off-canvas .button--danger:hover,
+#drupal-off-canvas .button--danger:focus,
+#drupal-off-canvas .button--danger:active {
+  color: #ff2a00;
+  text-decoration: none;
+  text-shadow: none;
+}
+#drupal-off-canvas .button--danger:disabled,
+#drupal-off-canvas .button--danger.is-disabled {
+  color: #737373;
+  cursor: default;
+}
diff --git a/core/modules/outside_in/css/off-canvas.css b/core/misc/dialog/off-canvas.css
similarity index 69%
rename from core/modules/outside_in/css/off-canvas.css
rename to core/misc/dialog/off-canvas.css
index d7f3258b26..52a8b9e079 100644
--- a/core/modules/outside_in/css/off-canvas.css
+++ b/core/misc/dialog/off-canvas.css
@@ -1,8 +1,6 @@
 /**
  * @file
  * CSS for off-canvas dialog.
- *
- * @todo Move CSS into core dialog library https://www.drupal.org/node/2784443.
  */
 
 /* Position the off-canvas dialog container outside the right of the viewport. */
@@ -23,14 +21,14 @@
   text-align: right;
 }
 
-/* Position the dialog-off-canvas tray container outside the right of the viewport. */
+/* Position the off-canvas dialog container outside the right of the viewport. */
 .ui-dialog-off-canvas {
   box-sizing: border-box;
   height: 100%;
   overflow: visible;
 }
 
-/* Wrap the form that's inside the dialog-off-canvas tray. */
+/* Wrap the form that's inside the off-canvas dialog. */
 .ui-dialog-off-canvas #drupal-off-canvas {
   padding: 0 20px;
   /* Prevent horizontal scrollbar. */
@@ -42,15 +40,15 @@
 }
 
 /*
- * Force the tray to be 100% width at the same breakpoint the dialog system uses
- * to expand dialog widths.
+ * Force the off-canvas dialog to be 100% width at the same breakpoint the
+ * dialog system uses to expand dialog widths.
  */
 @media all and (max-width: 48em) { /* 768px */
   .ui-dialog.ui-dialog-off-canvas {
     width: 100% !important;
   }
-  /* When tray is at 100% width stop the body from scrolling */
-  .js-tray-open {
+  /* When off-canvas dialog is at 100% width stop the body from scrolling */
+  .js-off-canvas-dialog-open {
     height: 100%;
     overflow-y: hidden;
   }
diff --git a/core/modules/outside_in/css/off-canvas.details.css b/core/misc/dialog/off-canvas.details.css
similarity index 93%
rename from core/modules/outside_in/css/off-canvas.details.css
rename to core/misc/dialog/off-canvas.details.css
index dcac6a5b04..fcd526f0b0 100644
--- a/core/modules/outside_in/css/off-canvas.details.css
+++ b/core/misc/dialog/off-canvas.details.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Visual styling for summary and details in the Settings Tray module's off canvas tray.
+ * Visual styling for summary and details in the off-canvas dialog.
  */
 
 #drupal-off-canvas details,
diff --git a/core/modules/outside_in/css/off-canvas.dropbutton.css b/core/misc/dialog/off-canvas.dropbutton.css
similarity index 98%
rename from core/modules/outside_in/css/off-canvas.dropbutton.css
rename to core/misc/dialog/off-canvas.dropbutton.css
index e467a4f341..7211dceaf5 100644
--- a/core/modules/outside_in/css/off-canvas.dropbutton.css
+++ b/core/misc/dialog/off-canvas.dropbutton.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Styles for dropbuttons in the off-canvas tray.
+ * Styles for dropbuttons in the off-canvas dialog.
  */
 
 #drupal-off-canvas .dropbutton-wrapper,
@@ -241,7 +241,7 @@
   content: '.';
   display: block;
   color: transparent;
-  background: transparent url(../../../misc/icons/ffffff/pencil.svg) no-repeat center;
+  background: transparent url(../icons/ffffff/pencil.svg) no-repeat center;
   background-size: 14px;
 }
 
diff --git a/core/modules/outside_in/js/off-canvas.es6.js b/core/misc/dialog/off-canvas.es6.js
similarity index 92%
rename from core/modules/outside_in/js/off-canvas.es6.js
rename to core/misc/dialog/off-canvas.es6.js
index 480561a7c6..a82ff22b29 100644
--- a/core/modules/outside_in/js/off-canvas.es6.js
+++ b/core/misc/dialog/off-canvas.es6.js
@@ -2,16 +2,12 @@
  * @file
  * Drupal's off-canvas library.
  *
- * @todo This functionality should extracted into a new core library or a part
- *  of the current drupal.dialog.ajax library.
- *  https://www.drupal.org/node/2784443
- *
  * @private
  */
 
 (function ($, Drupal, debounce, displace) {
   // The minimum width to use body displace needs to match the width at which
-  // the tray will be %100 width. @see outside_in.module.css
+  // the off-canvas dialog will be 100% width. @see core/misc/dialog/off-canvas.css
   const minDisplaceWidth = 768;
 
   /**
@@ -136,14 +132,13 @@
         },
         'dialog:beforecreate': function (event, dialog, $element, settings) {
           if ($element.is('#drupal-off-canvas')) {
-            $('body').addClass('js-tray-open');
+            $('body').addClass('js-off-canvas-dialog-open');
             // @see http://api.jqueryui.com/position/
             settings.position = {
               my: 'left top',
               at: `${edge} top`,
               of: window,
             };
-            settings.dialogClass += ' ui-dialog-off-canvas';
             // Applies initial height to dialog based on window height.
             // See http://api.jqueryui.com/dialog for all dialog options.
             settings.height = $(window).height();
@@ -151,7 +146,7 @@
         },
         'dialog:beforeclose': function (event, dialog, $element) {
           if ($element.is('#drupal-off-canvas')) {
-            $('body').removeClass('js-tray-open');
+            $('body').removeClass('js-off-canvas-dialog-open');
             // Remove all *.off-canvas events
             $(document).off('.off-canvas');
             $(window).off('.off-canvas');
diff --git a/core/misc/dialog/off-canvas.form.css b/core/misc/dialog/off-canvas.form.css
new file mode 100644
index 0000000000..217f3d1f2c
--- /dev/null
+++ b/core/misc/dialog/off-canvas.form.css
@@ -0,0 +1,136 @@
+/**
+ * @file
+ * Visual styling for forms in the off-canvas dialog.
+ */
+
+#drupal-off-canvas form {
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+  color: #ddd;
+}
+#drupal-off-canvas input[type="checkbox"] {
+  -webkit-appearance: checkbox;
+}
+#drupal-off-canvas input[type="radio"] {
+  -webkit-appearance: radio;
+}
+#drupal-off-canvas select {
+  -webkit-appearance: menulist;
+  -moz-appearance: menulist;
+}
+#drupal-off-canvas option {
+  display: block;
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+}
+#drupal-off-canvas label {
+  line-height: normal;
+  font-family: inherit;
+  font-size: 12px;
+  font-weight: bold;
+  color: #ddd;
+}
+#drupal-off-canvas .visually-hidden {
+  opacity: 0;
+  height: 0;
+  width: 0;
+  letter-spacing: -2em;
+}
+#drupal-off-canvas .description,
+#drupal-off-canvas .form-item .description,
+#drupal-off-canvas .details-description {
+  color: #ddd;
+  margin-top: 5px;
+  font-family: inherit;
+  font-size: 12px;
+  font-style: normal;
+}
+#drupal-off-canvas .details-wrapper .description {
+  color: #bbb;
+}
+#drupal-off-canvas .form-item {
+  margin-bottom: 10px;
+  margin-top: 10px;
+}
+/* Set size and position for all inputs. */
+#drupal-off-canvas .form-select,
+#drupal-off-canvas .form-text,
+#drupal-off-canvas .form-tel,
+#drupal-off-canvas .form-email,
+#drupal-off-canvas .form-url,
+#drupal-off-canvas .form-search,
+#drupal-off-canvas .form-number,
+#drupal-off-canvas .form-color,
+#drupal-off-canvas .form-file,
+#drupal-off-canvas .form-textarea,
+#drupal-off-canvas .form-date,
+#drupal-off-canvas .form-time {
+  box-sizing: border-box;
+  max-width: 100%;
+  padding: 6px;
+  margin: 5px 0 0 0;
+  border-width: 1px;
+  border-radius: 2px;
+  display: block;
+  font-family: inherit;
+  font-size: 14px;
+  color: #333;
+  line-height: 16px;
+  cursor: pointer;
+}
+/* Reduce contrast for fields against dark background. */
+#drupal-off-canvas .form-text,
+#drupal-off-canvas .form-tel,
+#drupal-off-canvas .form-email,
+#drupal-off-canvas .form-url,
+#drupal-off-canvas .form-search,
+#drupal-off-canvas .form-number,
+#drupal-off-canvas .form-color,
+#drupal-off-canvas .form-file,
+#drupal-off-canvas .form-textarea,
+#drupal-off-canvas .form-date,
+#drupal-off-canvas .form-time {
+  box-shadow: inset 0 1px 2px rgba(0, 0, 0, .125);
+  background-color: #eee;
+  border-color: #333;
+  color: #595959;
+}
+#drupal-off-canvas .form-text:focus,
+#drupal-off-canvas .form-tel:focus,
+#drupal-off-canvas .form-email:focus,
+#drupal-off-canvas .form-url:focus,
+#drupal-off-canvas .form-search:focus,
+#drupal-off-canvas .form-number:focus,
+#drupal-off-canvas .form-color:focus,
+#drupal-off-canvas .form-file:focus,
+#drupal-off-canvas .form-textarea:focus,
+#drupal-off-canvas .form-date:focus,
+#drupal-off-canvas .form-time:focus {
+  border-color: #40b6ff;
+  box-shadow: inset 0 1px 3px rgba(0, 0, 0, .125), 0 0 8px #40b6ff;
+  background-color: #fff;
+}
+#drupal-off-canvas td .form-item,
+#drupal-off-canvas td .form-select {
+  margin: 0;
+}
+#drupal-off-canvas .form-file {
+  margin-bottom: 5px;
+  width: 100%;
+}
+#drupal-off-canvas .form-actions {
+  text-align: center;
+  margin: 10px 0;
+}
+#drupal-off-canvas .ui-autocomplete {
+  background-color: white;
+  position: absolute;
+  top: 0;
+  left: 0;
+  cursor: default;
+}
+#drupal-off-canvas .ui-autocomplete li {
+  display: block;
+}
+#drupal-off-canvas .ui-autocomplete li a {
+  color: #595959 !important;
+  padding: 5px;
+}
diff --git a/core/modules/outside_in/js/off-canvas.js b/core/misc/dialog/off-canvas.js
similarity index 94%
rename from core/modules/outside_in/js/off-canvas.js
rename to core/misc/dialog/off-canvas.js
index 85a9e53675..0e645b1193 100644
--- a/core/modules/outside_in/js/off-canvas.js
+++ b/core/misc/dialog/off-canvas.js
@@ -87,21 +87,20 @@
         },
         'dialog:beforecreate': function dialogBeforecreate(event, dialog, $element, settings) {
           if ($element.is('#drupal-off-canvas')) {
-            $('body').addClass('js-tray-open');
+            $('body').addClass('js-off-canvas-dialog-open');
 
             settings.position = {
               my: 'left top',
               at: edge + ' top',
               of: window
             };
-            settings.dialogClass += ' ui-dialog-off-canvas';
 
             settings.height = $(window).height();
           }
         },
         'dialog:beforeclose': function dialogBeforeclose(event, dialog, $element) {
           if ($element.is('#drupal-off-canvas')) {
-            $('body').removeClass('js-tray-open');
+            $('body').removeClass('js-off-canvas-dialog-open');
 
             $(document).off('.off-canvas');
             $(window).off('.off-canvas');
diff --git a/core/modules/outside_in/css/off-canvas.motion.css b/core/misc/dialog/off-canvas.motion.css
similarity index 60%
rename from core/modules/outside_in/css/off-canvas.motion.css
rename to core/misc/dialog/off-canvas.motion.css
index e8df8dbbd2..335bd2fe5a 100644
--- a/core/modules/outside_in/css/off-canvas.motion.css
+++ b/core/misc/dialog/off-canvas.motion.css
@@ -4,10 +4,6 @@
  *
  * Motion effects are in a separate file so that they can be easily turned off
  * to improve performance if desired.
- *
- * @todo Move motion effects file into a core Off-Canvas library and add a
- *   configuration option for browser rendering performance to disable this
- *   file: https://www.drupal.org/node/2784443.
  */
 
 .dialog-off-canvas__main-canvas {
diff --git a/core/modules/outside_in/css/off-canvas.reset.css b/core/misc/dialog/off-canvas.reset.css
similarity index 100%
rename from core/modules/outside_in/css/off-canvas.reset.css
rename to core/misc/dialog/off-canvas.reset.css
diff --git a/core/modules/outside_in/css/off-canvas.table.css b/core/misc/dialog/off-canvas.table.css
similarity index 96%
rename from core/modules/outside_in/css/off-canvas.table.css
rename to core/misc/dialog/off-canvas.table.css
index 3a6e749757..7e7cd2e662 100644
--- a/core/modules/outside_in/css/off-canvas.table.css
+++ b/core/misc/dialog/off-canvas.table.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Visual styling for tables in the Settings Tray module's off canvas tray.
+ * Visual styling for tables in the off-canvas dialog.
  */
 
 #drupal-off-canvas table * {
diff --git a/core/modules/outside_in/css/off-canvas.tabledrag.css b/core/misc/dialog/off-canvas.tabledrag.css
similarity index 94%
rename from core/modules/outside_in/css/off-canvas.tabledrag.css
rename to core/misc/dialog/off-canvas.tabledrag.css
index 4f6f9bee5e..9b5e97343f 100644
--- a/core/modules/outside_in/css/off-canvas.tabledrag.css
+++ b/core/misc/dialog/off-canvas.tabledrag.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Table drag behavior for Settings Tray module.
+ * Table drag behavior for off-canvas dialog.
  *
  * @see tabledrag.js
  */
@@ -38,7 +38,7 @@
 }
 #drupal-off-canvas a.tabledrag-handle .handle {
   /* Use lighter drag icon against dark background. */
-  background-image: url(../../../misc/icons/bebebe/move.svg);
+  background-image: url(../icons/bebebe/move.svg);
   background-repeat: no-repeat;
   background-position: center;
   height: auto;
@@ -49,7 +49,7 @@
 }
 #drupal-off-canvas .draggable a.tabledrag-handle:hover .handle,
 #drupal-off-canvas .draggable a.tabledrag-handle:focus .handle {
-  background-image: url(../../../misc/icons/787878/move.svg);
+  background-image: url(../icons/787878/move.svg);
   text-decoration: none;
 }
 #drupal-off-canvas tr td {
diff --git a/core/modules/outside_in/css/off-canvas.theme.css b/core/misc/dialog/off-canvas.theme.css
similarity index 90%
rename from core/modules/outside_in/css/off-canvas.theme.css
rename to core/misc/dialog/off-canvas.theme.css
index 47bdcfbbcf..3f43266e4d 100644
--- a/core/modules/outside_in/css/off-canvas.theme.css
+++ b/core/misc/dialog/off-canvas.theme.css
@@ -10,7 +10,7 @@
   z-index: 501;
 }
 
-/* Style the tray header. */
+/* Style the off-canvas dialog header. */
 .ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar {
   padding: 1em;
   background: #2d2d2d;
@@ -25,7 +25,7 @@
   visibility: hidden;
 }
 .ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar-close {
-  background-image: url(../../../misc/icons/bebebe/ex.svg);
+  background-image: url(../icons/bebebe/ex.svg);
   background-position: center center;
   background-repeat: no-repeat;
   background-color: transparent;
@@ -36,7 +36,7 @@
   transition: background .5s ease;
 }
 .ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar-close:hover {
-  background-image: url(../../../misc/icons/ffffff/ex.svg);
+  background-image: url(../icons/ffffff/ex.svg);
 }
 [dir="rtl"] .ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar-close {
   left: 1em;
@@ -60,7 +60,7 @@
   padding-right: 30px;
 }
 .ui-dialog.ui-dialog-off-canvas .ui-dialog-title:before {
-  background: transparent url(../../../misc/icons/ffffff/pencil.svg) no-repeat scroll center center;
+  background: transparent url(../icons/ffffff/pencil.svg) no-repeat scroll center center;
   background-size: 100% auto;
   content: '';
   display: block;
diff --git a/core/modules/outside_in/css/outside_in.motion.css b/core/modules/outside_in/css/outside_in.motion.css
index 4bdd236321..620180a4a7 100644
--- a/core/modules/outside_in/css/outside_in.motion.css
+++ b/core/modules/outside_in/css/outside_in.motion.css
@@ -16,7 +16,7 @@
 /* Transition the editables on the page, their contextual links and their hover states. */
 .dialog-off-canvas__main-canvas .contextual,
 .dialog-off-canvas__main-canvas .js-outside-in-edit-mode .outside-in-editable,
-.dialog-off-canvas__main-canvas.js-tray-open .js-outside-in-edit-mode .outside-in-editable {
+.dialog-off-canvas__main-canvas.js-off-canvas-dialog-open .js-outside-in-edit-mode .outside-in-editable {
   -webkit-transition: all .7s ease;
   -moz-transition: all .7s ease;
   transition: all .7s ease;
diff --git a/core/modules/outside_in/outside_in.libraries.yml b/core/modules/outside_in/outside_in.libraries.yml
index 06e24a8291..64e1eddd19 100644
--- a/core/modules/outside_in/outside_in.libraries.yml
+++ b/core/modules/outside_in/outside_in.libraries.yml
@@ -17,29 +17,3 @@ drupal.outside_in:
     - core/drupal
     - core/jquery.once
     - core/drupal.ajax
-drupal.off_canvas:
-  version: VERSION
-  js:
-    js/off-canvas.js: {}
-  css:
-    base:
-      css/off-canvas.reset.css: {}
-      css/off-canvas.base.css: {}
-      css/off-canvas.css: {}
-      css/off-canvas.theme.css: { group: 200 }
-    component:
-      css/off-canvas.motion.css: {}
-      css/off-canvas.button.css: {}
-      css/off-canvas.form.css: {}
-      css/off-canvas.table.css: {}
-      css/off-canvas.details.css: {}
-      css/off-canvas.tabledrag.css: {}
-      css/off-canvas.dropbutton.css: {}
-
-  dependencies:
-    - core/jquery
-    - core/drupal
-    - core/drupal.ajax
-    - core/drupal.announce
-    - core/drupal.dialog
-    - core/drupal.dialog.ajax
diff --git a/core/modules/outside_in/outside_in.module b/core/modules/outside_in/outside_in.module
index acded3af11..eb4ada9f5c 100644
--- a/core/modules/outside_in/outside_in.module
+++ b/core/modules/outside_in/outside_in.module
@@ -44,7 +44,7 @@ function outside_in_contextual_links_view_alter(&$element, $items) {
       $element['#links']['outside-inblock-configure']['title'] = t('Quick edit settings');
     }
 
-    $element['#attached']['library'][] = 'outside_in/drupal.off_canvas';
+    $element['#attached']['library'][] = 'core/drupal.dialog.off_canvas';
   }
 }
 
@@ -61,26 +61,6 @@ function outside_in_block_view_alter(array &$build) {
 }
 
 /**
- * Implements hook_element_info_alter().
- */
-function outside_in_element_info_alter(&$type) {
-  if (isset($type['page'])) {
-    $type['page']['#theme_wrappers']['outside_in_page_wrapper'] = ['#weight' => -1000];
-  }
-}
-
-/**
- * Implements hook_theme().
- */
-function outside_in_theme() {
-  return [
-    'outside_in_page_wrapper' => [
-      'variables' => ['children' => NULL],
-    ],
-  ];
-}
-
-/**
  * Implements hook_entity_type_build().
  */
 function outside_in_entity_type_build(array &$entity_types) {
diff --git a/core/modules/outside_in/outside_in.services.yml b/core/modules/outside_in/outside_in.services.yml
deleted file mode 100644
index ce8214697a..0000000000
--- a/core/modules/outside_in/outside_in.services.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-services:
-  main_content_renderer.off_canvas:
-    class: Drupal\outside_in\Render\MainContent\OffCanvasRenderer
-    arguments: ['@title_resolver', '@renderer']
-    tags:
-      - { name: render.main_content_renderer, format: drupal_dialog.off_canvas }
diff --git a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
index daf3d1f737..b59b89f3e4 100644
--- a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
+++ b/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInBlockFormTest.php
@@ -5,6 +5,7 @@
 use Drupal\block\Entity\Block;
 use Drupal\block_content\Entity\BlockContent;
 use Drupal\block_content\Entity\BlockContentType;
+use Drupal\Tests\system\FunctionalJavascript\OffCanvasTestBase;
 use Drupal\user\Entity\Role;
 
 /**
@@ -12,7 +13,7 @@
  *
  * @group outside_in
  */
-class OutsideInBlockFormTest extends OutsideInJavascriptTestBase {
+class OutsideInBlockFormTest extends OffCanvasTestBase {
 
   const TOOLBAR_EDIT_LINK_SELECTOR = '#toolbar-bar div.contextual-toolbar-tab button';
 
@@ -528,4 +529,59 @@ public function testValidationMessages() {
     }
   }
 
+  /**
+   * Clicks a contextual link.
+   *
+   * @todo Remove this function when related trait added in
+   *   https://www.drupal.org/node/2821724.
+   *
+   * @param string $selector
+   *   The selector for the element that contains the contextual link.
+   * @param string $link_locator
+   *   The link id, title, or text.
+   * @param bool $force_visible
+   *   If true then the button will be forced to visible so it can be clicked.
+   */
+  protected function clickContextualLink($selector, $link_locator, $force_visible = TRUE) {
+    if ($force_visible) {
+      $this->toggleContextualTriggerVisibility($selector);
+    }
+
+    $element = $this->getSession()->getPage()->find('css', $selector);
+    $element->find('css', '.contextual button')->press();
+    $element->findLink($link_locator)->click();
+
+    if ($force_visible) {
+      $this->toggleContextualTriggerVisibility($selector);
+    }
+  }
+
+  /**
+   * Toggles the visibility of a contextual trigger.
+   *
+   * @todo Remove this function when related trait added in
+   *   https://www.drupal.org/node/2821724.
+   *
+   * @param string $selector
+   *   The selector for the element that contains the contextual link.
+   */
+  protected function toggleContextualTriggerVisibility($selector) {
+    // Hovering over the element itself with should be enough, but does not
+    // work. Manually remove the visually-hidden class.
+    $this->getSession()->executeScript("jQuery('{$selector} .contextual .trigger').toggleClass('visually-hidden');");
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getTestThemes() {
+    $themes = parent::getTestThemes();
+    // Remove 'seven' theme. Setting Tray "Edit Mode" will not work with 'seven'
+    // because it removes all contextual links the off-canvas dialog should.
+    if (($key = array_search('seven', $themes)) !== FALSE) {
+      unset($themes[$key]);
+    }
+    return $themes;
+  }
+
 }
diff --git a/core/modules/outside_in/src/Tests/Ajax/OffCanvasDialogTest.php b/core/modules/system/src/Tests/Ajax/OffCanvasDialogTest.php
similarity index 85%
rename from core/modules/outside_in/src/Tests/Ajax/OffCanvasDialogTest.php
rename to core/modules/system/src/Tests/Ajax/OffCanvasDialogTest.php
index ce3356f112..6d7ddbb9d4 100644
--- a/core/modules/outside_in/src/Tests/Ajax/OffCanvasDialogTest.php
+++ b/core/modules/system/src/Tests/Ajax/OffCanvasDialogTest.php
@@ -1,30 +1,22 @@
 <?php
 
-namespace Drupal\outside_in\Tests\Ajax;
+namespace Drupal\system\Tests\Ajax;
 
 use Drupal\ajax_test\Controller\AjaxTestController;
 use Drupal\Core\EventSubscriber\MainContentViewSubscriber;
-use Drupal\system\Tests\Ajax\AjaxTestBase;
 
 /**
  * Performs tests on opening and manipulating dialogs via AJAX commands.
  *
- * @group outside_in
+ * @group Ajax
  */
 class OffCanvasDialogTest extends AjaxTestBase {
 
-  /**
-   * Modules to enable.
-   *
-   * @var array
-   */
-  public static $modules = ['outside_in'];
 
   /**
    * Test sending AJAX requests to open and manipulate off-canvas dialog.
    */
   public function testDialog() {
-    $this->drupalLogin($this->drupalCreateUser(['administer contact forms']));
     // Ensure the elements render without notices or exceptions.
     $this->drupalGet('ajax-test/dialog');
 
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index d327d4e74b..cb366ac49c 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -268,6 +268,9 @@ function system_theme() {
       ],
       'template' => 'entity-add-list',
     ],
+    'off_canvas_page_wrapper' => [
+      'variables' => ['children' => NULL],
+    ],
   ]);
 }
 
@@ -1515,3 +1518,12 @@ function system_query_entity_reference_alter(AlterableInterface $query) {
   $handler = $query->getMetadata('entity_reference_selection_handler');
   $handler->entityQueryAlter($query);
 }
+
+/**
+ * Implements hook_element_info_alter().
+ */
+function system_element_info_alter(&$type) {
+  if (isset($type['page'])) {
+    $type['page']['#theme_wrappers']['off_canvas_page_wrapper'] = ['#weight' => -1000];
+  }
+}
diff --git a/core/modules/outside_in/templates/outside-in-page-wrapper.html.twig b/core/modules/system/templates/off-canvas-page-wrapper.html.twig
similarity index 58%
rename from core/modules/outside_in/templates/outside-in-page-wrapper.html.twig
rename to core/modules/system/templates/off-canvas-page-wrapper.html.twig
index 11c7f5311d..98b67ba2c2 100644
--- a/core/modules/outside_in/templates/outside-in-page-wrapper.html.twig
+++ b/core/modules/system/templates/off-canvas-page-wrapper.html.twig
@@ -5,13 +5,13 @@
  *
  * For consistent wrapping to {{ page }} render in all themes. The
  * "data-off-canvas-main-canvas" attribute is required by the off-canvas dialog.
- * This is used by the outside_in/drupal.off_canvas library to select the
- * "main canvas" page element as opposed to the "off canvas" which is the tray
+ * This is used by the core/drupal.dialog.off_canvas library to select the
+ * "main canvas" page element as opposed to the "off canvas" which is the dialog
  * itself. The "main canvas" element must be resized according to the width of
- * the "off canvas" tray so that no portion of the "main canvas" is obstructed
- * by the tray. The tray can vary in width when opened and can be resized by the
- * user. The "data-off-canvas-main-canvas" attribute cannot be removed without
- * breaking the off-canvas dialog functionality.
+ * the "off canvas" dialog so that no portion of the "main canvas" is obstructed
+ * by the off-canvas dialog. The off-canvas dialog can vary in width when opened
+ * and can be resized by the user. The "data-off-canvas-main-canvas" attribute
+ * cannot be removed without breaking the off-canvas dialog functionality.
  *
  * Available variables:
  * - children: Contains the child elements of the page.
@@ -20,7 +20,7 @@
  */
 #}
 {% if children %}
-  <div class="dialog-off-canvas__main-canvas" data-off-canvas-main-canvas >
+  <div class="dialog-off-canvas__main-canvas" data-off-canvas-main-canvas>
     {{ children }}
   </div>
 {% endif %}
diff --git a/core/modules/outside_in/tests/modules/off_canvas_test/off_canvas_test.info.yml b/core/modules/system/tests/modules/off_canvas_test/off_canvas_test.info.yml
similarity index 76%
rename from core/modules/outside_in/tests/modules/off_canvas_test/off_canvas_test.info.yml
rename to core/modules/system/tests/modules/off_canvas_test/off_canvas_test.info.yml
index 8c6cc80242..9680b1842d 100644
--- a/core/modules/outside_in/tests/modules/off_canvas_test/off_canvas_test.info.yml
+++ b/core/modules/system/tests/modules/off_canvas_test/off_canvas_test.info.yml
@@ -4,6 +4,3 @@ description: 'Provides off-canvas test links.'
 package: Testing
 version: VERSION
 core: 8.x
-dependencies:
-  - block
-  - outside_in
diff --git a/core/modules/outside_in/tests/modules/off_canvas_test/off_canvas_test.routing.yml b/core/modules/system/tests/modules/off_canvas_test/off_canvas_test.routing.yml
similarity index 100%
rename from core/modules/outside_in/tests/modules/off_canvas_test/off_canvas_test.routing.yml
rename to core/modules/system/tests/modules/off_canvas_test/off_canvas_test.routing.yml
diff --git a/core/modules/outside_in/tests/modules/off_canvas_test/src/Controller/TestController.php b/core/modules/system/tests/modules/off_canvas_test/src/Controller/TestController.php
similarity index 88%
rename from core/modules/outside_in/tests/modules/off_canvas_test/src/Controller/TestController.php
rename to core/modules/system/tests/modules/off_canvas_test/src/Controller/TestController.php
index 6164b06fc2..ea310fa0bd 100644
--- a/core/modules/outside_in/tests/modules/off_canvas_test/src/Controller/TestController.php
+++ b/core/modules/system/tests/modules/off_canvas_test/src/Controller/TestController.php
@@ -53,11 +53,6 @@ public function linksDisplay() {
           'data-dialog-type' => 'dialog',
           'data-dialog-renderer' => 'off_canvas',
         ],
-        '#attached' => [
-          'library' => [
-            'outside_in/drupal.outside_in',
-          ],
-        ],
       ],
       'off_canvas_link_2' => [
         '#title' => 'Click Me 2!',
@@ -71,11 +66,6 @@ public function linksDisplay() {
             'width' => 555,
           ]),
         ],
-        '#attached' => [
-          'library' => [
-            'outside_in/drupal.outside_in',
-          ],
-        ],
       ],
       'other_dialog_links' => [
         '#title' => 'Display more links!',
@@ -86,10 +76,10 @@ public function linksDisplay() {
           'data-dialog-type' => 'dialog',
           'data-dialog-renderer' => 'off_canvas',
         ],
-        '#attached' => [
-          'library' => [
-            'outside_in/drupal.outside_in',
-          ],
+      ],
+      '#attached' => [
+        'library' => [
+          'core/drupal.dialog.ajax',
         ],
       ],
     ];
@@ -129,11 +119,6 @@ public function otherDialogLinks() {
           ],
         ],
       ],
-      '#attached' => [
-        'library' => [
-          'outside_in/drupal.outside_in',
-        ],
-      ],
     ];
   }
 
diff --git a/core/modules/outside_in/tests/src/FunctionalJavascript/OffCanvasTest.php b/core/modules/system/tests/src/FunctionalJavascript/OffCanvasTest.php
similarity index 89%
rename from core/modules/outside_in/tests/src/FunctionalJavascript/OffCanvasTest.php
rename to core/modules/system/tests/src/FunctionalJavascript/OffCanvasTest.php
index 2f64d9fe2c..80b1980eea 100644
--- a/core/modules/outside_in/tests/src/FunctionalJavascript/OffCanvasTest.php
+++ b/core/modules/system/tests/src/FunctionalJavascript/OffCanvasTest.php
@@ -1,22 +1,18 @@
 <?php
 
-namespace Drupal\Tests\outside_in\FunctionalJavascript;
+namespace Drupal\Tests\system\FunctionalJavascript;
 
 /**
  * Tests the off-canvas dialog functionality.
  *
  * @group outside_in
  */
-class OffCanvasTest extends OutsideInJavascriptTestBase {
+class OffCanvasTest extends OffCanvasTestBase {
 
   /**
    * {@inheritdoc}
    */
   public static $modules = [
-    'block',
-    'system',
-    'toolbar',
-    'outside_in',
     'off_canvas_test',
   ];
 
@@ -48,7 +44,7 @@ public function testOffCanvasLinks() {
         $web_assert->elementExists('css', '#drupal-off-canvas');
         // Check that response text is on page.
         $web_assert->pageTextContains("Thing $link_index says hello");
-        $off_canvas_tray = $this->getTray();
+        $off_canvas_tray = $this->getOffCanvasDialog();
 
         // Check that tray is visible.
         $this->assertEquals(TRUE, $off_canvas_tray->isVisible());
@@ -111,13 +107,4 @@ public function testNarrowWidth() {
     }
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  protected function getTestThemes() {
-    // Add 'seven' theme. Setting Tray "Edit Mode" will not work with 'seven'
-    // because it removes all contextual links the off-canvas dialog should.
-    return array_merge(parent::getTestThemes(), ['seven']);
-  }
-
 }
diff --git a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInJavascriptTestBase.php b/core/modules/system/tests/src/FunctionalJavascript/OffCanvasTestBase.php
similarity index 54%
rename from core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInJavascriptTestBase.php
rename to core/modules/system/tests/src/FunctionalJavascript/OffCanvasTestBase.php
index 2ce2bf64d6..6b74b5efcb 100644
--- a/core/modules/outside_in/tests/src/FunctionalJavascript/OutsideInJavascriptTestBase.php
+++ b/core/modules/system/tests/src/FunctionalJavascript/OffCanvasTestBase.php
@@ -1,13 +1,13 @@
 <?php
 
-namespace Drupal\Tests\outside_in\FunctionalJavascript;
+namespace Drupal\Tests\system\FunctionalJavascript;
 
 use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
 
 /**
- * Base class contains common test functionality for the Settings Tray module.
+ * Base class contains common test functionality for the Off-canvas dialog.
  */
-abstract class OutsideInJavascriptTestBase extends JavascriptTestBase {
+abstract class OffCanvasTestBase extends JavascriptTestBase {
 
   /**
    * {@inheritdoc}
@@ -15,8 +15,8 @@
   protected function drupalGet($path, array $options = [], array $headers = []) {
     $return = parent::drupalGet($path, $options, $headers);
 
-    // After the page loaded we need to additionally wait until the settings
-    // tray Ajax activity is done.
+    // After the page loaded we need to additionally wait until the off-canvas
+    // dialog Ajax activity is done.
     $this->assertSession()->assertWaitOnAjaxRequest();
 
     return $return;
@@ -41,6 +41,9 @@ protected function enableTheme($theme) {
    */
   protected function waitForOffCanvasToOpen() {
     $web_assert = $this->assertSession();
+    // Wait just slightly longer than the off-canvas dialog CSS animation.
+    // @see core/misc/dialog/off-canvas.motion.css
+    $this->getSession()->wait(800);
     $web_assert->assertWaitOnAjaxRequest();
     $this->assertElementVisibleAfterWait('css', '#drupal-off-canvas');
   }
@@ -57,10 +60,10 @@ protected function waitForOffCanvasToClose() {
    *
    * @return \Behat\Mink\Element\NodeElement|null
    */
-  protected function getTray() {
-    $tray = $this->getSession()->getPage()->find('css', '.ui-dialog[aria-describedby="drupal-off-canvas"]');
-    $this->assertEquals(FALSE, empty($tray), 'The tray was found.');
-    return $tray;
+  protected function getOffCanvasDialog() {
+    $off_canvas_dialog = $this->getSession()->getPage()->find('css', '.ui-dialog[aria-describedby="drupal-off-canvas"]');
+    $this->assertEquals(FALSE, empty($off_canvas_dialog), 'The off-canvas dialog was found.');
+    return $off_canvas_dialog;
   }
 
   /**
@@ -70,6 +73,8 @@ protected function getTray() {
    *   CSS selector.
    * @param int $timeout
    *   (optional) Timeout in milliseconds, defaults to 10000.
+   *
+   * @todo Remove in https://www.drupal.org/node/2892440.
    */
   protected function waitForNoElement($selector, $timeout = 10000) {
     $condition = "(jQuery('$selector').length == 0)";
@@ -77,55 +82,13 @@ protected function waitForNoElement($selector, $timeout = 10000) {
   }
 
   /**
-   * Clicks a contextual link.
-   *
-   * @todo Remove this function when related trait added in
-   *   https://www.drupal.org/node/2821724.
-   *
-   * @param string $selector
-   *   The selector for the element that contains the contextual link.
-   * @param string $link_locator
-   *   The link id, title, or text.
-   * @param bool $force_visible
-   *   If true then the button will be forced to visible so it can be clicked.
-   */
-  protected function clickContextualLink($selector, $link_locator, $force_visible = TRUE) {
-    if ($force_visible) {
-      $this->toggleContextualTriggerVisibility($selector);
-    }
-
-    $element = $this->getSession()->getPage()->find('css', $selector);
-    $element->find('css', '.contextual button')->press();
-    $element->findLink($link_locator)->click();
-
-    if ($force_visible) {
-      $this->toggleContextualTriggerVisibility($selector);
-    }
-  }
-
-  /**
-   * Toggles the visibility of a contextual trigger.
-   *
-   * @todo Remove this function when related trait added in
-   *   https://www.drupal.org/node/2821724.
-   *
-   * @param string $selector
-   *   The selector for the element that contains the contextual link.
-   */
-  protected function toggleContextualTriggerVisibility($selector) {
-    // Hovering over the element itself with should be enough, but does not
-    // work. Manually remove the visually-hidden class.
-    $this->getSession()->executeScript("jQuery('{$selector} .contextual .trigger').toggleClass('visually-hidden');");
-  }
-
-  /**
    * Get themes to test.
    *
    * @return string[]
    *   Theme names to test.
    */
   protected function getTestThemes() {
-    return ['bartik', 'stark', 'classy', 'stable'];
+    return ['bartik', 'stark', 'classy', 'stable', 'seven'];
   }
 
   /**
diff --git a/core/modules/outside_in/tests/src/Unit/Ajax/OpenOffCanvasDialogCommandTest.php b/core/tests/Drupal/Tests/Core/Ajax/OpenOffCanvasDialogCommandTest.php
similarity index 81%
rename from core/modules/outside_in/tests/src/Unit/Ajax/OpenOffCanvasDialogCommandTest.php
rename to core/tests/Drupal/Tests/Core/Ajax/OpenOffCanvasDialogCommandTest.php
index 314fd1c2f3..e2d933a657 100644
--- a/core/modules/outside_in/tests/src/Unit/Ajax/OpenOffCanvasDialogCommandTest.php
+++ b/core/tests/Drupal/Tests/Core/Ajax/OpenOffCanvasDialogCommandTest.php
@@ -1,13 +1,13 @@
 <?php
 
-namespace Drupal\Tests\outside_in\Unit\Ajax;
+namespace Drupal\Tests\Core\Ajax;
 
-use Drupal\outside_in\Ajax\OpenOffCanvasDialogCommand;
+use Drupal\Core\Ajax\OpenOffCanvasDialogCommand;
 use Drupal\Tests\UnitTestCase;
 
 /**
- * @coversDefaultClass \Drupal\outside_in\Ajax\OpenOffCanvasDialogCommand
- * @group outside_in
+ * @coversDefaultClass \Drupal\Core\Ajax\OpenOffCanvasDialogCommand
+ * @group Ajax
  */
 class OpenOffCanvasDialogCommandTest extends UnitTestCase {
 
diff --git a/core/themes/stable/css/core/dialog/off-canvas.base.css b/core/themes/stable/css/core/dialog/off-canvas.base.css
new file mode 100644
index 0000000000..25f1acbf71
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.base.css
@@ -0,0 +1,238 @@
+/*
+ * @file
+ * Set base styles for the off-canvas dialog.
+ */
+
+/* Set some global attributes. */
+#drupal-off-canvas *,
+#drupal-off-canvas *:not(div) {
+  background: #444;
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+  color: #ddd;
+}
+
+/* Generic elements. */
+#drupal-off-canvas a,
+#drupal-off-canvas .link {
+  border-bottom: none;
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+  font-size: inherit;
+  font-weight: normal;
+  color: #85bef4;
+  text-decoration: none;
+  transition: color .5s ease;
+}
+
+#drupal-off-canvas a:focus,
+#drupal-off-canvas .link:focus,
+#drupal-off-canvas a:hover,
+#drupal-off-canvas .link:hover {
+  outline: none;
+  color: #46a0f5;
+}
+#drupal-off-canvas hr {
+  height: 1px;
+  background: #cccccc;
+}
+#drupal-off-canvas summary,
+#drupal-off-canvas .fieldgroup:not(.form-composite) > legend {
+  font-weight: bold;
+}
+#drupal-off-canvas h1,
+#drupal-off-canvas .heading-a {
+  display: block;
+  font-weight: bold;
+  font-size: 1.625em;
+  line-height: 1.875em;
+}
+#drupal-off-canvas h2,
+#drupal-off-canvas .heading-b {
+  display: block;
+  font-weight: bold;
+  margin: 10px 0;
+  font-size: 1.385em;
+}
+#drupal-off-canvas h3,
+#drupal-off-canvas .heading-c {
+  display: block;
+  font-weight: bold;
+  margin: 10px 0;
+  font-size: 1.231em;
+}
+#drupal-off-canvas h4,
+#drupal-off-canvas .heading-d {
+  display: block;
+  font-weight: bold;
+  margin: 10px 0;
+  font-size: 1.154em;
+}
+#drupal-off-canvas h5,
+#drupal-off-canvas .heading-e {
+  display: block;
+  font-weight: bold;
+  margin: 10px 0;
+  font-size: 1.077em;
+}
+#drupal-off-canvas h6,
+#drupal-off-canvas .heading-f {
+  display: block;
+  font-weight: bold;
+  margin: 10px 0;
+  font-size: 1.077em;
+}
+#drupal-off-canvas p {
+  margin: 1em 0;
+}
+#drupal-off-canvas dl {
+  margin: 0 0 20px;
+}
+#drupal-off-canvas dl dd,
+#drupal-off-canvas dl dl {
+  margin-left: 20px; /* LTR */
+  margin-bottom: 10px;
+}
+[dir="rtl"] #drupal-off-canvas dl dd,
+[dir="rtl"] #drupal-off-canvas dl dl {
+  margin-right: 20px;
+}
+#drupal-off-canvas blockquote {
+  margin: 1em 40px;
+}
+#drupal-off-canvas address {
+  font-style: italic;
+}
+#drupal-off-canvas u,
+#drupal-off-canvas ins {
+  text-decoration: underline;
+}
+#drupal-off-canvas s,
+#drupal-off-canvas strike,
+#drupal-off-canvas del {
+  text-decoration: line-through;
+}
+#drupal-off-canvas big {
+  font-size: larger;
+}
+#drupal-off-canvas small {
+  font-size: smaller;
+}
+#drupal-off-canvas sub {
+  vertical-align: sub;
+  font-size: smaller;
+  line-height: normal;
+}
+#drupal-off-canvas sup {
+  vertical-align: super;
+  font-size: smaller;
+  line-height: normal;
+}
+#drupal-off-canvas nobr {
+  white-space: nowrap;
+}
+#drupal-off-canvas abbr,
+#drupal-off-canvas acronym {
+  border-bottom: dotted 1px;
+  background: transparent;
+}
+
+#drupal-off-canvas ul {
+  list-style-type: disc;
+  list-style-image: none;
+}
+[dir="rtl"] #drupal-off-canvas .messages__list {
+  margin-right: 0;
+}
+#drupal-off-canvas ol {
+  list-style-type: decimal;
+}
+#drupal-off-canvas ul li,
+#drupal-off-canvas ol li {
+  display: block;
+}
+#drupal-off-canvas quote,
+#drupal-off-canvas code {
+  margin: 20px 0;
+}
+#drupal-off-canvas pre {
+  margin: 20px 0;
+  white-space: pre-wrap;
+}
+
+/* Classes for hidden and visually hidden elements. See hidden.module.css. */
+#drupal-off-canvas .hidden {
+  display: none;
+}
+#drupal-off-canvas .visually-hidden {
+  position: absolute !important;
+  clip: rect(1px, 1px, 1px, 1px);
+  overflow: hidden;
+  height: 1px;
+  width: 1px;
+  word-wrap: normal;
+}
+#drupal-off-canvas .visually-hidden.focusable:active,
+#drupal-off-canvas .visually-hidden.focusable:focus {
+  position: static !important;
+  clip: auto;
+  overflow: visible;
+  height: auto;
+  width: auto;
+}
+#drupal-off-canvas .invisible {
+  visibility: hidden;
+}
+
+/* Some system classes. See system.admin.css. */
+#drupal-off-canvas .panel {
+  padding: 5px 5px 15px;
+}
+#drupal-off-canvas .panel__description {
+  margin: 0 0 3px;
+  padding: 2px 0 3px 0;
+}
+#drupal-off-canvas .compact-link {
+  margin: 0 0 10px 0;
+}
+#drupal-off-canvas small .admin-link:before {
+  content: ' [';
+}
+#drupal-off-canvas small .admin-link:after {
+  content: ']';
+}
+
+/* Override jquery UI */
+#drupal-off-canvas .ui-widget-content a {
+  color: #85bef4 !important;
+}
+
+/* Message styles */
+#drupal-off-canvas .messages {
+  background: no-repeat 10px 17px;
+}
+[dir="rtl"] #drupal-off-canvas .messages {
+  background-position: right 10px top 17px;
+}
+#drupal-off-canvas .messages abbr {
+  color: #444;
+}
+#drupal-off-canvas .messages--status {
+  background-color: #f3faef;
+  background-image: url(../../../images/core/icons/73b355/check.svg);
+  color: #325e1c;
+}
+#drupal-off-canvas .messages--warning {
+  background-color: #fdf8ed;
+  background-image: url(../../../images/core/icons/e29700/warning.svg);
+  color: #734c00;
+}
+
+#drupal-off-canvas .messages--error {
+  background-color: #fcf4f2;
+  background-image: url(../../../images/core/icons/e32700/error.svg);
+  color: #a51b00;
+}
+
+#drupal-off-canvas .messages--error div[role="alert"] {
+  background: transparent;
+  color: inherit;
+}
diff --git a/core/modules/outside_in/css/off-canvas.button.css b/core/themes/stable/css/core/dialog/off-canvas.button.css
similarity index 96%
rename from core/modules/outside_in/css/off-canvas.button.css
rename to core/themes/stable/css/core/dialog/off-canvas.button.css
index 4f7987aa7c..e37b7ac4e0 100644
--- a/core/modules/outside_in/css/off-canvas.button.css
+++ b/core/themes/stable/css/core/dialog/off-canvas.button.css
@@ -1,7 +1,7 @@
 /**
- * Visual styling for buttons in the off canvas tray.
+ * Visual styling for buttons in the off-canvas dialog.
  *
- * See seven/css/components/buttons.css
+ * @see seven/css/components/buttons.css
  */
 
 #drupal-off-canvas button,
diff --git a/core/themes/stable/css/core/dialog/off-canvas.css b/core/themes/stable/css/core/dialog/off-canvas.css
new file mode 100644
index 0000000000..52a8b9e079
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.css
@@ -0,0 +1,55 @@
+/**
+ * @file
+ * CSS for off-canvas dialog.
+ */
+
+/* Position the off-canvas dialog container outside the right of the viewport. */
+.ui-dialog-off-canvas {
+  box-sizing: border-box;
+  height: 100%;
+  overflow: visible;
+}
+
+/* Wrap the form that's inside the off-canvas dialog. */
+.ui-dialog-off-canvas .ui-dialog-content {
+  padding: 0 20px;
+  /* Prevent horizontal scrollbar. */
+  overflow-x: hidden;
+  overflow-y: auto;
+}
+[dir="rtl"] .ui-dialog-off-canvas .ui-dialog-content {
+  text-align: right;
+}
+
+/* Position the off-canvas dialog container outside the right of the viewport. */
+.ui-dialog-off-canvas {
+  box-sizing: border-box;
+  height: 100%;
+  overflow: visible;
+}
+
+/* Wrap the form that's inside the off-canvas dialog. */
+.ui-dialog-off-canvas #drupal-off-canvas {
+  padding: 0 20px;
+  /* Prevent horizontal scrollbar. */
+  overflow-x: hidden;
+  overflow-y: auto;
+}
+[dir="rtl"] .ui-dialog-off-canvas #drupal-off-canvas {
+  text-align: right;
+}
+
+/*
+ * Force the off-canvas dialog to be 100% width at the same breakpoint the
+ * dialog system uses to expand dialog widths.
+ */
+@media all and (max-width: 48em) { /* 768px */
+  .ui-dialog.ui-dialog-off-canvas {
+    width: 100% !important;
+  }
+  /* When off-canvas dialog is at 100% width stop the body from scrolling */
+  .js-off-canvas-dialog-open {
+    height: 100%;
+    overflow-y: hidden;
+  }
+}
diff --git a/core/themes/stable/css/core/dialog/off-canvas.details.css b/core/themes/stable/css/core/dialog/off-canvas.details.css
new file mode 100644
index 0000000000..fcd526f0b0
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.details.css
@@ -0,0 +1,61 @@
+/**
+ * @file
+ * Visual styling for summary and details in the off-canvas dialog.
+ */
+
+#drupal-off-canvas details,
+#drupal-off-canvas summary {
+  display: block;
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+}
+#drupal-off-canvas details,
+#drupal-off-canvas summary,
+#drupal-off-canvas .ui-dialog-content {
+  background: #474747;
+  color: #ddd;
+}
+#drupal-off-canvas summary a {
+  color: #ddd;
+  padding-top: 0;
+  padding-bottom: 0;
+}
+#drupal-off-canvas summary a:hover,
+#drupal-off-canvas summary a:focus {
+  color: #fff;
+}
+#drupal-off-canvas details,
+#drupal-off-canvas summary,
+#drupal-off-canvas .details-wrapper {
+  border-width: 0;
+  /* Cancel out the padding of the parent. */
+  margin: 0 -20px;
+  padding: 0 20px;
+}
+#drupal-off-canvas summary {
+  text-shadow: none;
+  padding: 10px 20px;
+  font-size: 14px;
+  transition: all .5s ease;
+}
+#drupal-off-canvas summary:hover,
+#drupal-off-canvas summary:focus {
+  background-color: #222;
+  outline: none;
+}
+#drupal-off-canvas details[open] {
+  padding-bottom: 10px;
+}
+#drupal-off-canvas details[open] > summary {
+  background-color: #333;
+  color: #eee;
+}
+#drupal-off-canvas details[open] > summary:hover {
+  background-color: #222;
+  color: #fff;
+}
+#drupal-off-canvas details .placeholder {
+  font: inherit;
+  color: inherit;
+  font-style: italic;
+  background: transparent;
+}
diff --git a/core/themes/stable/css/core/dialog/off-canvas.dropbutton.css b/core/themes/stable/css/core/dialog/off-canvas.dropbutton.css
new file mode 100644
index 0000000000..99f5c61a9d
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.dropbutton.css
@@ -0,0 +1,291 @@
+/**
+ * @file
+ * Styles for dropbuttons in the off-canvas dialog.
+ */
+
+#drupal-off-canvas .dropbutton-wrapper,
+#drupal-off-canvas .dropbutton-widget {
+  -webkit-appearance: none;
+  -moz-appearance: none;
+  display: block;
+  position: static;
+  transition: none;
+}
+#drupal-off-canvas .dropbutton-widget {
+  margin: 0;
+  padding: 0;
+  border: 0;
+  background: #277abd;
+  border-radius: 1em;
+  font-weight: 600;
+  color: #fff;
+  text-transform: none;
+  text-decoration: none;
+  text-align: center;
+  line-height: normal;
+  cursor: pointer;
+  transition: background .5s ease;
+}
+#drupal-off-canvas .dropbutton-widget:hover {
+  background: #2b8bd8;
+}
+
+/*
+ * Style dropbutton single.
+ */
+
+#drupal-off-canvas .dropbutton-single .dropbutton-action a {
+  padding: 0;
+  /* Overlap icon for trigger. */
+  margin-top: -2em;
+  height: 2.2em;
+  cursor: pointer;
+}
+#drupal-off-canvas .dropbutton-single .dropbutton-action:hover,
+#drupal-off-canvas .dropbutton-single .dropbutton-action:focus,
+#drupal-off-canvas .dropbutton-single .dropbutton-action a:hover,
+#drupal-off-canvas .dropbutton-single .dropbutton-action a:focus {
+  text-decoration: none;
+  outline: none;
+}
+#drupal-off-canvas .dropbutton-widget .dropbutton {
+  margin: 0;
+  overflow: hidden;
+  padding: 0;
+}
+#drupal-off-canvas .dropbutton li,
+#drupal-off-canvas .dropbutton a {
+  display: block;
+  width: auto;
+  padding: 4px 0;
+  text-align: left;
+  color: #555;
+  outline: none;
+}
+#drupal-off-canvas .dropbutton li:hover,
+#drupal-off-canvas .dropbutton li:focus,
+#drupal-off-canvas .dropbutton a:hover,
+#drupal-off-canvas .dropbutton a:focus {
+  background: transparent;
+  color: #333;
+  outline: none;
+}
+
+/*
+ * Style dropbutton multiple.
+ */
+
+#drupal-off-canvas .dropbutton-multiple .dropbutton-widget {
+  width: 2em;
+  height: 2em;
+}
+#drupal-off-canvas .dropbutton-multiple .dropbutton-widget:hover {
+  background-color: #2b8bd8;
+}
+
+/* Hide the other actions until the dropbutton is triggered. */
+#drupal-off-canvas .dropbutton-multiple .dropbutton .secondary-action {
+  display: none;
+}
+
+/* The toggle to expand the button. */
+#drupal-off-canvas .dropbutton-toggle {
+  position: absolute;
+  top: 0;
+  right: 0; /* LTR */
+  bottom: 0;
+  display: block;
+  width: 2em;
+  color: #fff;
+  text-indent: 110%;
+  white-space: nowrap;
+}
+#drupal-off-canvas .dropbutton-toggle button {
+  display: block;
+  height: 100%;
+  width: 100%;
+  margin: 0;
+  padding: 0;
+  border: 0 solid transparent;
+  border-bottom-right-radius: 1em; /* LTR */
+  border-top-right-radius: 1em; /* LTR */
+  cursor: pointer;
+}
+#drupal-off-canvas .dropbutton-toggle button:hover,
+#drupal-off-canvas .dropbutton-toggle button:focus {
+  outline: none;
+}
+
+/* The toggle arrow. */
+#drupal-off-canvas .dropbutton-arrow {
+  position: absolute;
+  display: block;
+  height: 0;
+  width: 0;
+  margin-top: 0;
+  border-bottom-color: transparent;
+  border-left-color: transparent;
+  border-right-color: transparent;
+  border-style: solid;
+  border-width: 0.3333em 0.3333em 0;
+  color: #fff;
+  line-height: 0;
+  overflow: hidden;
+}
+#drupal-off-canvas span.dropbutton-arrow {
+  top: 7px;
+  right: 7px; /* LTR */
+  background: transparent;
+}
+#drupal-off-canvas span.dropbutton-arrow:hover {
+  background: transparent;
+}
+
+#drupal-off-canvas .dropbutton-action > .js-form-submit.form-submit,
+#drupal-off-canvas .dropbutton-toggle button {
+  position: relative;
+  text-shadow: none;
+}
+
+/*
+ * Dropbuttons when in a table cell.
+ */
+
+/* Make sure table cell doesn't collapse around absolute positioned dropbutton. */
+#drupal-off-canvas td .dropbutton-single {
+  min-width: 2em;
+}
+#drupal-off-canvas td .dropbutton-multiple {
+  min-width: 2em;
+  padding-right: 0;
+  padding-left: 0;
+  margin-right: 0;
+  margin-left: 0;
+  border: 0;
+}
+#drupal-off-canvas td .dropbutton-multiple .dropbutton-action a,
+#drupal-off-canvas td .dropbutton-multiple .dropbutton-action input,
+#drupal-off-canvas td .dropbutton-multiple .dropbutton-action button {
+  width: auto;
+  padding: 0;
+  font-size: inherit;
+}
+#drupal-off-canvas td .dropbutton-wrapper {
+  margin-bottom: 0;
+}
+
+/* Push the widget to the right so text expands left. */
+#drupal-off-canvas td .dropbutton-widget {
+  position: absolute;
+  right: 12px; /* LTR */
+  padding: 0;
+  background: #277abd none;
+}
+
+/* Push the wrapper to the right edge of the td. */
+#drupal-off-canvas td .dropbutton-single,
+#drupal-off-canvas td .dropbutton-multiple {
+  float: right; /* LTR */
+  padding-right: 0;
+  margin-right: 0;
+  max-width: initial;
+  min-width: initial;
+  position: relative;
+}
+#drupal-off-canvas td .dropbutton-widget .dropbutton {
+  margin: 0;
+  width: 2em;
+  height: 2em;
+  overflow: hidden;
+  background: transparent;
+}
+
+/* Push text out of the way. */
+#drupal-off-canvas td .dropbutton-multiple li,
+#drupal-off-canvas td .dropbutton-multiple a {
+  margin-left: -9999px;
+  background: transparent;
+}
+#drupal-off-canvas td .dropbutton-multiple.open .dropbutton li,
+#drupal-off-canvas td .dropbutton-multiple.open .dropbutton a {
+  margin-left: 0;
+  width: auto;
+  color: #fff;
+}
+
+/* Collapse the button to a circle. */
+#drupal-off-canvas td .dropbutton-toggle {
+  width: 2em;
+  height: 2em;
+  border-radius: 1em;
+}
+#drupal-off-canvas td .dropbutton-wrapper .dropbutton-widget .dropbutton-toggle button {
+  border: 0;
+  background: transparent;
+}
+
+/* Prevent list item from expanding it's container. */
+#drupal-off-canvas td ul.dropbutton li.edit {
+  width: 2em;
+  height: 2em;
+}
+
+/* Make li text transparent above icon so it's clickable. */
+#drupal-off-canvas td .dropbutton-single li.edit.dropbutton-action > a {
+  color: transparent;
+  z-index: 1;
+}
+
+/* Put pencil icon in place of hidden 'edit' text on single buttons. */
+#drupal-off-canvas td .dropbutton-single .edit:before {
+  content: '.';
+  display: block;
+  color: transparent;
+  background: transparent url(../../../images/core/icons/ffffff/pencil.svg) no-repeat center;
+  background-size: 14px;
+}
+
+/* Dropbutton when triggered expands to show secondary items. */
+#drupal-off-canvas .dropbutton-multiple.open {
+  z-index: 100;
+}
+
+/* Create visual separation if there is an adjacent button. */
+#drupal-off-canvas .dropbutton-multiple.open .dropbutton-widget {
+  box-shadow: 0 3px 3px 2px rgba(0,0,0,0.5);
+}
+
+/* Triggered dropbutton expands to show secondary items. */
+#drupal-off-canvas .dropbutton-multiple.open,
+#drupal-off-canvas .dropbutton-multiple.open .dropbutton-widget {
+  display: block;
+  width: auto;
+  height: auto;
+  max-width: none;
+  min-width: 0;
+  padding: 0;
+  overflow: visible;
+}
+
+/* Triggered dropbutton in td expands to show secondary items. */
+#drupal-off-canvas td .dropbutton-multiple.open .dropbutton,
+#drupal-off-canvas .dropbutton-multiple.open .dropbutton .secondary-action {
+  display: block;
+  width: auto;
+  height: auto;
+  padding-right: 1em; /* LTR */
+}
+[dir="rtl"] #drupal-off-canvas td .dropbutton-multiple.open .dropbutton {
+  padding-left: 1em;
+  padding-right: inherit;
+}
+#drupal-off-canvas .dropbutton-multiple.open .dropbutton li a {
+  padding: 2px 1em;
+}
+
+/* When open, the toggle arrow points upward. */
+#drupal-off-canvas .dropbutton-multiple.open span.dropbutton-arrow {
+  border-bottom: 0.3333em solid;
+  border-top-color: transparent;
+  top: 2px;
+}
diff --git a/core/modules/outside_in/css/off-canvas.form.css b/core/themes/stable/css/core/dialog/off-canvas.form.css
similarity index 97%
rename from core/modules/outside_in/css/off-canvas.form.css
rename to core/themes/stable/css/core/dialog/off-canvas.form.css
index 254b2c74e9..b47dbcc6f2 100644
--- a/core/modules/outside_in/css/off-canvas.form.css
+++ b/core/themes/stable/css/core/dialog/off-canvas.form.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Visual styling for forms in the Settings Tray module's off canvas tray.
+ * Visual styling for forms in the off-canvas dialog.
  */
 
 #drupal-off-canvas form {
diff --git a/core/themes/stable/css/core/dialog/off-canvas.motion.css b/core/themes/stable/css/core/dialog/off-canvas.motion.css
new file mode 100644
index 0000000000..335bd2fe5a
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.motion.css
@@ -0,0 +1,13 @@
+/**
+ * @file
+ * Motion effects for off-canvas dialog.
+ *
+ * Motion effects are in a separate file so that they can be easily turned off
+ * to improve performance if desired.
+ */
+
+.dialog-off-canvas__main-canvas {
+  -webkit-transition: all .7s ease;
+  -moz-transition: all .7s ease;
+  transition: all .7s ease;
+}
diff --git a/core/themes/stable/css/core/dialog/off-canvas.reset.css b/core/themes/stable/css/core/dialog/off-canvas.reset.css
new file mode 100644
index 0000000000..cd87eda9c9
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.reset.css
@@ -0,0 +1,386 @@
+/**
+ * @file
+ * Reset most HTML elements styles for the off-canvas dialog.
+ *
+ * This is a generic reset. Drupal-specific classes are reset in components.
+ */
+
+/**
+ * Do not include div in then initial overrides because including div will
+ * cause the need for many more overrides in this file.
+ */
+#drupal-off-canvas *:not(div),
+#drupal-off-canvas *:after,
+#drupal-off-canvas *:before {
+  all: initial;
+  box-sizing: border-box;
+  text-shadow: none;
+  -webkit-font-smoothing: antialiased;
+  -webkit-tap-highlight-color: initial;
+}
+
+/* Reset size and position on elements. */
+#drupal-off-canvas a,
+#drupal-off-canvas abbr,
+#drupal-off-canvas acronym,
+#drupal-off-canvas address,
+#drupal-off-canvas applet,
+#drupal-off-canvas article,
+#drupal-off-canvas aside,
+#drupal-off-canvas audio,
+#drupal-off-canvas b,
+#drupal-off-canvas big,
+#drupal-off-canvas blockquote,
+#drupal-off-canvas body,
+#drupal-off-canvas canvas,
+#drupal-off-canvas caption,
+#drupal-off-canvas cite,
+#drupal-off-canvas code,
+#drupal-off-canvas dd,
+#drupal-off-canvas del,
+#drupal-off-canvas dfn,
+#drupal-off-canvas dialog,
+#drupal-off-canvas dl,
+#drupal-off-canvas dt,
+#drupal-off-canvas em,
+#drupal-off-canvas embed,
+#drupal-off-canvas fieldset,
+#drupal-off-canvas figcaption,
+#drupal-off-canvas figure,
+#drupal-off-canvas footer,
+#drupal-off-canvas form,
+#drupal-off-canvas h1,
+#drupal-off-canvas h2,
+#drupal-off-canvas h3,
+#drupal-off-canvas h4,
+#drupal-off-canvas h5,
+#drupal-off-canvas h6,
+#drupal-off-canvas header,
+#drupal-off-canvas hgroup,
+#drupal-off-canvas hr,
+#drupal-off-canvas html,
+#drupal-off-canvas i,
+#drupal-off-canvas iframe,
+#drupal-off-canvas img,
+#drupal-off-canvas ins,
+#drupal-off-canvas kbd,
+#drupal-off-canvas label,
+#drupal-off-canvas legend,
+#drupal-off-canvas li,
+#drupal-off-canvas main,
+#drupal-off-canvas mark,
+#drupal-off-canvas menu,
+#drupal-off-canvas meter,
+#drupal-off-canvas nav,
+#drupal-off-canvas object,
+#drupal-off-canvas ol,
+#drupal-off-canvas output,
+#drupal-off-canvas p,
+#drupal-off-canvas pre,
+#drupal-off-canvas progress,
+#drupal-off-canvas q,
+#drupal-off-canvas rp,
+#drupal-off-canvas rt,
+#drupal-off-canvas s,
+#drupal-off-canvas samp,
+#drupal-off-canvas section,
+#drupal-off-canvas small,
+#drupal-off-canvas span,
+#drupal-off-canvas strike,
+#drupal-off-canvas strong,
+#drupal-off-canvas sub,
+#drupal-off-canvas sup,
+#drupal-off-canvas table,
+#drupal-off-canvas tbody,
+#drupal-off-canvas td,
+#drupal-off-canvas tfoot,
+#drupal-off-canvas th,
+#drupal-off-canvas thead,
+#drupal-off-canvas time,
+#drupal-off-canvas tr,
+#drupal-off-canvas tt,
+#drupal-off-canvas u,
+#drupal-off-canvas ul,
+#drupal-off-canvas var,
+#drupal-off-canvas video,
+#drupal-off-canvas xmp {
+  border: 0;
+  margin: 0;
+  padding: 0;
+  font-size: 100%;
+}
+
+/*
+ * Override the default (display: inline) for browsers that do not recognize HTML5 tags.
+ * IE8 (and lower) requires a shiv: http://ejohn.org/blog/html5-shiv
+ */
+#drupal-off-canvas article,
+#drupal-off-canvas aside,
+#drupal-off-canvas figcaption,
+#drupal-off-canvas figure,
+#drupal-off-canvas footer,
+#drupal-off-canvas header,
+#drupal-off-canvas hgroup,
+#drupal-off-canvas main,
+#drupal-off-canvas menu,
+#drupal-off-canvas nav,
+#drupal-off-canvas section {
+  display: block;
+  line-height: normal;
+  border-radius: 0;
+}
+
+/*
+ * Makes browsers agree.
+ * IE + Opera = font-weight: bold.
+ * Gecko + WebKit = font-weight: bolder.
+ */
+#drupal-off-canvas b,
+#drupal-off-canvas strong {
+  font-weight: bold;
+}
+
+#drupal-off-canvas em,
+#drupal-off-canvas i {
+  font-style: italic;
+}
+
+#drupal-off-canvas img {
+  color: transparent;
+  font-size: 0;
+  vertical-align: middle;
+}
+
+#drupal-off-canvas ul,
+#drupal-off-canvas ol {
+  list-style: none;
+}
+
+/* reset table styling. */
+#drupal-off-canvas table {
+  border-collapse: collapse;
+  border-spacing: 0;
+}
+#drupal-off-canvas table thead,
+#drupal-off-canvas table tbody,
+#drupal-off-canvas table tbody tr:nth-child(even),
+#drupal-off-canvas table tbody tr:nth-child(odd),
+#drupal-off-canvas table tfoot {
+  border: 0;
+  background: none;
+  background-color: transparent;
+}
+#drupal-off-canvas th,
+#drupal-off-canvas td,
+#drupal-off-canvas caption {
+  font-weight: normal;
+}
+#drupal-off-canvas q {
+  quotes: none;
+}
+#drupal-off-canvas q:before,
+#drupal-off-canvas q:after {
+  content: none;
+}
+#drupal-off-canvas sub,
+#drupal-off-canvas sup,
+#drupal-off-canvas small {
+  font-size: 75%;
+}
+#drupal-off-canvas sub,
+#drupal-off-canvas sup {
+  line-height: 0;
+  position: relative;
+  vertical-align: baseline;
+}
+#drupal-off-canvas sub {
+  bottom: -0.25em;
+}
+#drupal-off-canvas sup {
+  top: -0.5em;
+}
+
+/*
+ * For IE9. Without, occasionally draws shapes
+ * outside the boundaries of <svg> rectangle.
+ */
+#drupal-off-canvas svg {
+  overflow: hidden;
+}
+
+/* Specific resets for inputs. */
+#drupal-off-canvas input[type="search"]::-webkit-search-decoration {
+  display: none;
+}
+#drupal-off-canvas input {
+  margin: 0;
+  padding: 0;
+}
+#drupal-off-canvas input[type="checkbox"],
+#drupal-off-canvas input[type="radio"] {
+  position: static;
+  margin: 0;
+}
+#drupal-off-canvas input:invalid,
+#drupal-off-canvas button:invalid,
+#drupal-off-canvas select:invalid,
+#drupal-off-canvas textarea:invalid,
+#drupal-off-canvas input:focus,
+#drupal-off-canvas button:focus,
+#drupal-off-canvas select:focus,
+#drupal-off-canvas textarea:focus,
+#drupal-off-canvas input[type="file"]:focus,
+#drupal-off-canvas input[type="file"]:active,
+#drupal-off-canvas input[type="radio"]:focus,
+#drupal-off-canvas input[type="radio"]:active,
+#drupal-off-canvas input[type="checkbox"]:focus,
+#drupal-off-canvas input[type="checkbox"]:active {
+  box-shadow: none;
+  z-index: 1;
+}
+#drupal-off-canvas input[role="button"] {
+  cursor: pointer;
+}
+#drupal-off-canvas button,
+#drupal-off-canvas input[type="reset"],
+#drupal-off-canvas input[type="submit"],
+#drupal-off-canvas input[type="button"] {
+  -webkit-appearance: none;
+  -moz-appearance: none;
+  display: inline-block;
+  background-image: none;
+  border: 0;
+  outline: 0;
+  overflow: visible;
+  text-shadow: none;
+  text-decoration: none;
+  vertical-align: middle;
+  cursor: pointer;
+}
+#drupal-off-canvas button:hover,
+#drupal-off-canvas input[type="reset"]:hover,
+#drupal-off-canvas input[type="submit"]:hover,
+#drupal-off-canvas input[type="button"]:hover {
+  background-image: none;
+  text-decoration: none;
+}
+#drupal-off-canvas button:active,
+#drupal-off-canvas input[type="reset"]:active,
+#drupal-off-canvas input[type="submit"]:active,
+#drupal-off-canvas input[type="button"]:active {
+  background-image: none;
+  box-shadow: none;
+  border-color: grey;
+}
+#drupal-off-canvas button::-moz-focus-inner,
+#drupal-off-canvas input[type="reset"]::-moz-focus-inner,
+#drupal-off-canvas input[type="submit"]::-moz-focus-inner,
+#drupal-off-canvas input[type="button"]::-moz-focus-inner {
+  border: 0;
+  padding: 0;
+}
+#drupal-off-canvas textarea,
+#drupal-off-canvas select,
+#drupal-off-canvas input[type="date"],
+#drupal-off-canvas input[type="datetime"],
+#drupal-off-canvas input[type="datetime-local"],
+#drupal-off-canvas input[type="email"],
+#drupal-off-canvas input[type="month"],
+#drupal-off-canvas input[type="number"],
+#drupal-off-canvas input[type="password"],
+#drupal-off-canvas input[type="search"],
+#drupal-off-canvas input[type="tel"],
+#drupal-off-canvas input[type="text"],
+#drupal-off-canvas input[type="time"],
+#drupal-off-canvas input[type="url"],
+#drupal-off-canvas input[type="week"] {
+  height: auto;
+  vertical-align: middle;
+  border-radius: 0;
+}
+#drupal-off-canvas textarea[disabled],
+#drupal-off-canvas select[disabled],
+#drupal-off-canvas input[type="date"][disabled],
+#drupal-off-canvas input[type="datetime"][disabled],
+#drupal-off-canvas input[type="datetime-local"][disabled],
+#drupal-off-canvas input[type="email"][disabled],
+#drupal-off-canvas input[type="month"][disabled],
+#drupal-off-canvas input[type="number"][disabled],
+#drupal-off-canvas input[type="password"][disabled],
+#drupal-off-canvas input[type="search"][disabled],
+#drupal-off-canvas input[type="tel"][disabled],
+#drupal-off-canvas input[type="text"][disabled],
+#drupal-off-canvas input[type="time"][disabled],
+#drupal-off-canvas input[type="url"][disabled],
+#drupal-off-canvas input[type="week"][disabled] {
+  background-color: grey;
+}
+#drupal-off-canvas input[type="hidden"] {
+  visibility: hidden;
+}
+#drupal-off-canvas button[disabled],
+#drupal-off-canvas input[disabled],
+#drupal-off-canvas select[disabled],
+#drupal-off-canvas select[disabled] option,
+#drupal-off-canvas select[disabled] optgroup,
+#drupal-off-canvas textarea[disabled] {
+  box-shadow: none;
+  user-select: none;
+  cursor: default;
+}
+#drupal-off-canvas input:placeholder,
+#drupal-off-canvas textarea:placeholder {
+  color: grey;
+}
+#drupal-off-canvas textarea,
+#drupal-off-canvas select[size],
+#drupal-off-canvas select[multiple] {
+  height: auto;
+}
+#drupal-off-canvas select[size="0"],
+#drupal-off-canvas select[size="1"] {
+  height: auto;
+}
+#drupal-off-canvas textarea {
+  min-height: 40px;
+  overflow: auto;
+  resize: vertical;
+  width: 100%;
+}
+#drupal-off-canvas optgroup {
+  color: black;
+  font-style: normal;
+  font-weight: normal;
+}
+#drupal-off-canvas optgroup::-moz-focus-inner {
+  border: 0;
+  padding: 0;
+}
+#drupal-off-canvas * button {
+  background: none;
+  border: 1px solid;
+  border-color: grey;
+  color: black;
+  padding: 0;
+  text-decoration: none;
+  overflow: visible;
+  vertical-align: middle;
+  width: auto;
+}
+#drupal-off-canvas * textarea,
+#drupal-off-canvas * select,
+#drupal-off-canvas *:not(div) textarea,
+#drupal-off-canvas *:not(div) select {
+  background: white;
+  border: 1px solid;
+  border-color: grey;
+  color: black;
+  padding: 0;
+  vertical-align: top;
+}
+
+/* Bootstrap and other frameworks add color to selection. */
+#drupal-off-canvas ::selection {
+  background-color: rgba(175,175,175,0.5);
+  color: inherit;
+}
diff --git a/core/themes/stable/css/core/dialog/off-canvas.table.css b/core/themes/stable/css/core/dialog/off-canvas.table.css
new file mode 100644
index 0000000000..7e7cd2e662
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.table.css
@@ -0,0 +1,90 @@
+/**
+ * @file
+ * Visual styling for tables in the off-canvas dialog.
+ */
+
+#drupal-off-canvas table * {
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+}
+#drupal-off-canvas table {
+  display: table;
+  width: 100%;
+  min-width: calc(100% + 40px);
+  /* Cancel out the padding of the parent to make the table full width. */
+  margin: 0 -20px -10px -20px;
+  border: 0;
+  border-collapse: collapse;
+  font-size: 12px;
+  color: #ddd;
+}
+#drupal-off-canvas table thead {
+  display: table-header-group;
+}
+#drupal-off-canvas table tbody {
+  display: table-row-group;
+}
+#drupal-off-canvas tr {
+  display: table-row;
+}
+#drupal-off-canvas tr:hover td {
+  background-color: transparent;
+}
+
+#drupal-off-canvas td,
+#drupal-off-canvas th {
+  display: table-cell;
+  height: auto;
+  width: auto;
+  padding: 2px 8px;
+  vertical-align: middle;
+  border-bottom: 1px solid #777;
+  background-color: transparent;
+}
+[dir="rtl"] #drupal-off-canvas th,
+[dir="rtl"] #drupal-off-canvas td {
+  text-align: right;
+}
+#drupal-off-canvas th {
+  font-weight: bold;
+  color: #bbb;
+}
+#drupal-off-canvas th.checkbox,
+#drupal-off-canvas td.checkbox {
+  width: 20px;
+  padding: 0;
+  text-align: center;
+}
+#drupal-off-canvas div.checkbox.menu-enabled {
+  position: static;
+  display: inline;
+  width: auto;
+}
+#drupal-off-canvas th:first-child,
+#drupal-off-canvas td:first-child {
+  width: 150px;
+}
+/* For lack of a better class, using this to grab the operations th. */
+#drupal-off-canvas .tabledrag-has-colspan {
+  text-align: right;
+  padding-right: 20px;
+}
+#drupal-off-canvas td {
+  padding: 6px 8px;
+  color: #ddd;
+}
+/* Hide overflow with elipsis for links. */
+#drupal-off-canvas td a {
+  display: block;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  background: transparent;
+}
+#drupal-off-canvas tr td:first-child,
+#drupal-off-canvas tr th:first-child {
+  padding-left: 20px; /* LTR */
+}
+[dir="rtl"] #drupal-off-canvas tr td:first-child,
+[dir="rtl"] #drupal-off-canvas tr th:first-child {
+  padding-right: 20px;
+}
diff --git a/core/themes/stable/css/core/dialog/off-canvas.tabledrag.css b/core/themes/stable/css/core/dialog/off-canvas.tabledrag.css
new file mode 100644
index 0000000000..e6e90407a0
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.tabledrag.css
@@ -0,0 +1,122 @@
+/**
+ * @file
+ * Table drag behavior for off-canvas dialog.
+ *
+ * @see tabledrag.js
+ */
+
+#drupal-off-canvas .drag {
+  cursor: move;
+}
+#drupal-off-canvas tr.region-title {
+  font-weight: normal;
+}
+#drupal-off-canvas table .region-message {
+  color: #fff;
+}
+#drupal-off-canvas table .region-populated {
+  display: none;
+}
+#drupal-off-canvas .add-new .tabledrag-changed {
+  display: none;
+}
+#drupal-off-canvas .draggable a.tabledrag-handle {
+  background-image: none;
+  margin: 0 5px 0 0;
+  height: auto;
+  min-width: 20px;
+  padding: 0;
+  overflow: hidden;
+  float: left; /* LTR */
+  text-decoration: none;
+  cursor: move;
+}
+[dir="rtl"] #drupal-off-canvas .draggable a.tabledrag-handle {
+  float: right;
+  margin-right: 0;
+  margin-left: 5px;
+}
+#drupal-off-canvas a.tabledrag-handle .handle {
+  /* Use lighter drag icon against dark background. */
+  background-image: url(../../../images/core/icons/bebebe/move.svg);
+  background-repeat: no-repeat;
+  background-position: center;
+  height: auto;
+  margin: 0;
+  padding: 0;
+  width: auto;
+  background-color: transparent;
+}
+#drupal-off-canvas .draggable a.tabledrag-handle:hover .handle,
+#drupal-off-canvas .draggable a.tabledrag-handle:focus .handle {
+  background-image: url(../../../images/core/icons/787878/move.svg);
+  text-decoration: none;
+}
+#drupal-off-canvas tr td {
+  transition: background .3s ease;
+}
+
+#drupal-off-canvas tr td abbr {
+  margin-left: 5px; /* LTR */
+}
+
+[dir="rtl"] #drupal-off-canvas tr td abbr {
+  margin-left: 0;
+  margin-right: 5px;
+}
+#drupal-off-canvas tr:hover td {
+  background: #222;
+}
+#drupal-off-canvas tr.drag td {
+  background: #111;
+}
+#drupal-off-canvas tr.drag-previous td {
+  background: #000;
+}
+#drupal-off-canvas tr.drag-previous:hover td {
+  background: #222;
+}
+body div.tabledrag-changed-warning {
+  margin-bottom: 0.5em;
+  font-size: 14px;
+}
+#drupal-off-canvas .touchevents .draggable td {
+  padding: 0 10px;
+}
+#drupal-off-canvas .touchevents .draggable .menu-item__link {
+  display: inline-block;
+  padding: 10px 0;
+}
+#drupal-off-canvas .touchevents a.tabledrag-handle {
+  height: 44px;
+  width: 40px;
+}
+#drupal-off-canvas .touchevents a.tabledrag-handle .handle {
+  background-position: 40% 19px; /* LTR */
+  height: 21px;
+}
+[dir="rtl"] #drupal-off-canvas .touch a.tabledrag-handle .handle {
+  background-position: right 40% top 19px;
+}
+#drupal-off-canvas .touchevents .draggable.drag a.tabledrag-handle .handle {
+  background-position: 50% -32px;
+}
+#drupal-off-canvas .tabledrag-toggle-weight-wrapper {
+  padding-top: 10px;
+  text-align: right; /* LTR */
+}
+[dir="rtl"] #drupal-off-canvas .tabledrag-toggle-weight-wrapper {
+  text-align: left;
+}
+#drupal-off-canvas .indentation {
+  float: left; /* LTR */
+  height: auto;
+  margin: 0 3px 0 -10px; /* LTR */
+  padding: 0 0 0 10px; /* LTR */
+  width: auto;
+}
+[dir="rtl"] #drupal-off-canvas .indentation {
+  float: right;
+  margin: 0 -10px 0 3px;
+  padding: 0 10px 0 0;
+}
diff --git a/core/themes/stable/css/core/dialog/off-canvas.theme.css b/core/themes/stable/css/core/dialog/off-canvas.theme.css
new file mode 100644
index 0000000000..e215635d5e
--- /dev/null
+++ b/core/themes/stable/css/core/dialog/off-canvas.theme.css
@@ -0,0 +1,89 @@
+/* Style the dialog-off-canvas container. */
+.ui-dialog.ui-dialog-off-canvas {
+  background: #444;
+  border: 0 solid transparent;
+  border-radius: 0;
+  box-shadow: 0 0 4px 2px rgba(0, 0, 0, 0.3333);
+  padding: 0;
+  color: #ddd;
+  /* Layer the dialog just under the toolbar. */
+  z-index: 501;
+}
+
+/* Style the off-canvas dialog header. */
+.ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar {
+  padding: 1em;
+  background: #2d2d2d;
+  border: 0;
+  border-bottom: 1px solid #000;
+  border-radius: 0;
+  font-weight: normal;
+  color: #fff;
+}
+/* Hide the default Jquery UI dialog close button. */
+.ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar-close .ui-icon {
+  visibility: hidden;
+}
+.ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar-close {
+  background-image: url(../../../images/core/icons/bebebe/ex.svg);
+  background-position: center center;
+  background-repeat: no-repeat;
+  background-color: transparent;
+  border: 0;
+  position: absolute;
+  right: 1em;
+  -moz-transition: all .5s ease;
+  transition: background .5s ease;
+}
+.ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar-close:hover {
+  background-image: url(../../../images/core/icons/ffffff/ex.svg);
+}
+[dir="rtl"] .ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar-close {
+  left: 1em;
+  right: auto;
+}
+.ui-dialog.ui-dialog-off-canvas .ui-dialog-title {
+  margin: 0;
+  /* Push the text away from the icon. */
+  padding-left: 30px; /* LTR */
+  padding-right: 0; /* LTR */
+  /* Ensure that long titles do not overlap the close button. */
+  max-width: 210px;
+  font-size: 16px;
+  font-family: "Lucida Grande", 'Lucida Sans Unicode', 'liberation sans', sans-serif;
+  text-align: left; /* LTR */
+}
+[dir="rtl"] .ui-dialog.ui-dialog-off-canvas .ui-dialog-title {
+  float: right;
+  text-align: right;
+  padding-left: 0;
+  padding-right: 30px;
+}
+.ui-dialog.ui-dialog-off-canvas .ui-dialog-title:before {
+  background: transparent url(../../../images/core/icons/ffffff/pencil.svg) no-repeat scroll center center;
+  background-size: 100% auto;
+  content: '';
+  display: block;
+  height: 100%;
+  position: absolute;
+  left: 1em; /* LTR */
+  top: 0;
+  width: 20px;
+}
+[dir="rtl"] .ui-dialog.ui-dialog-off-canvas .ui-dialog-title:before {
+  left: auto;
+  right: 1em;
+}
+
+/* Override default styling from jquery UI. */
+#drupal-off-canvas .ui-state-default,
+#drupal-off-canvas .ui-widget-content .ui-state-default,
+#drupal-off-canvas .ui-widget-header .ui-state-default {
+  border: 0;
+  font-weight: normal;
+  font-size: 14px;
+  color: #333;
+}
+#drupal-off-canvas .ui-widget-content a {
+  color: #85bef4/*{fcContent}*/;
+}
diff --git a/core/themes/stable/stable.info.yml b/core/themes/stable/stable.info.yml
index 251ecbd534..1e437f9d4c 100644
--- a/core/themes/stable/stable.info.yml
+++ b/core/themes/stable/stable.info.yml
@@ -57,6 +57,22 @@ libraries-override:
       component:
         css/contextual.toolbar.css: css/contextual/contextual.toolbar.css
 
+  core/drupal.dialog.off_canvas:
+    css:
+      base:
+        misc/dialog/off-canvas.reset.css: css/core/dialog/off-canvas.reset.css
+        misc/dialog/off-canvas.base.css: css/core/dialog/off-canvas.base.css
+        misc/dialog/off-canvas.css: css/core/dialog/off-canvas.css
+        misc/dialog/off-canvas.theme.css: css/core/dialog/off-canvas.theme.css
+      component:
+        misc/dialog/off-canvas.motion.css: css/core/dialog/off-canvas.motion.css
+        misc/dialog/off-canvas.button.css: css/core/dialog/off-canvas.button.css
+        misc/dialog/off-canvas.form.css: css/core/dialog/off-canvas.form.css
+        misc/dialog/off-canvas.table.css: css/core/dialog/off-canvas.table.css
+        misc/dialog/off-canvas.details.css: css/core/dialog/off-canvas.details.css
+        misc/dialog/off-canvas.tabledrag.css: css/core/dialog/off-canvas.tabledrag.css
+        misc/dialog/off-canvas.dropbutton.css: css/core/dialog/off-canvas.dropbutton.css
+
   core/drupal.dropbutton:
     css:
       component:
diff --git a/core/themes/stable/templates/content/off-canvas-page-wrapper.html.twig b/core/themes/stable/templates/content/off-canvas-page-wrapper.html.twig
new file mode 100644
index 0000000000..11993371c4
--- /dev/null
+++ b/core/themes/stable/templates/content/off-canvas-page-wrapper.html.twig
@@ -0,0 +1,24 @@
+{#
+/**
+ * @file
+ * Theme override for page wrapper.
+ *
+ * For consistent wrapping to {{ page }} render in all themes. The
+ * "data-off-canvas-main-canvas" attribute is required by the off-canvas dialog.
+ * This is used by the core/drupal.dialog.off_canvas library to select the
+ * "main canvas" page element as opposed to the "off canvas" which is the dialog
+ * itself. The "main canvas" element must be resized according to the width of
+ * the "off canvas" dialog so that no portion of the "main canvas" is obstructed
+ * by the off-canvas dialog. The off-canvas dialog can vary in width when opened
+ * and can be resized by the user. The "data-off-canvas-main-canvas" attribute
+ * cannot be removed without breaking the off-canvas dialog functionality.
+ *
+ * Available variables:
+ * - children: Contains the child elements of the page.
+ */
+#}
+{% if children %}
+  <div class="dialog-off-canvas__main-canvas" data-off-canvas-main-canvas>
+    {{ children }}
+  </div>
+{% endif %}