diff --git a/core/misc/dialog/off-canvas.theme.css b/core/misc/dialog/off-canvas.theme.css
index ddc165ad2017a35b1caf54542828b29c3aaeb572..ba7759de683f4c6dc483cba773f56b285ac1410d 100644
--- a/core/misc/dialog/off-canvas.theme.css
+++ b/core/misc/dialog/off-canvas.theme.css
@@ -6,7 +6,6 @@
 /* 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;
@@ -14,6 +13,9 @@
   /* Layer the dialog just under the toolbar. */
   z-index: 501;
 }
+.ui-widget.ui-dialog.ui-dialog-off-canvas {
+  border: 1px solid transparent;
+}
 
 /* Style the off-canvas dialog header. */
 .ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar {
diff --git a/core/themes/stable/css/core/dialog/off-canvas.theme.css b/core/themes/stable/css/core/dialog/off-canvas.theme.css
index 351ef4723715d64f1004af0cd44e4f3bc5f3b17f..60175d35ab495fee823caaaf827c3ad593d53694 100644
--- a/core/themes/stable/css/core/dialog/off-canvas.theme.css
+++ b/core/themes/stable/css/core/dialog/off-canvas.theme.css
@@ -6,7 +6,6 @@
 /* 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;
@@ -14,6 +13,9 @@
   /* Layer the dialog just under the toolbar. */
   z-index: 501;
 }
+.ui-widget.ui-dialog.ui-dialog-off-canvas {
+  border: 1px solid transparent;
+}
 
 /* Style the off-canvas dialog header. */
 .ui-dialog.ui-dialog-off-canvas .ui-dialog-titlebar {