offcanvas-wrapper.patch

diff --git a/core/modules/outside_in/js/offcanvas.js b/core/modules/outside_in/js/offcanvas.js
index b3c4237..9522f03 100644
--- a/core/modules/outside_in/js/offcanvas.js
+++ b/core/modules/outside_in/js/offcanvas.js
@@ -106,6 +106,7 @@
 
         $element.dialog('widget').attr('data-offset-' + edge, '');
 
+        $element.closest('[role="dialog"]').wrap('<div class="offcanvas-wrapper"></div>');
         $(window)
           .on('resize.outsidein scroll.outsidein', eventData, debounce(resetSize, 100))
           .trigger('resize.outsidein');
@@ -119,6 +120,7 @@
           at: edge + ' top',
           of: window
         };
+
         settings.dialogClass = 'ui-dialog-offcanvas';
       }
     },
@@ -128,6 +130,11 @@
         $(window).off('.outsidein');
         $mainCanvasWrapper.css('padding-' + edge, 0);
       }
+    },
+    'dialog:afterclose': function (event, dialog, $element) {
+      if ($element.is('#drupal-offcanvas')) {
+        $('.offcanvas-wrapper').remove();
+      }
     }
   });