diff --git a/src/wp-admin/css/admin-menu.css b/src/wp-admin/css/admin-menu.css
index 0dc59c6e6b..66935f2448 100644
--- a/src/wp-admin/css/admin-menu.css
+++ b/src/wp-admin/css/admin-menu.css
@@ -11,6 +11,9 @@
 	top: 0;
 	bottom: -120px;
 	z-index: 1; /* positive z-index to avoid elastic scrolling woes in Safari */
+
+	/* Only visible in Windows High Contrast mode */
+	outline: 1px solid transparent;
 }
 
 .php-error #adminmenuback {
diff --git a/src/wp-includes/css/admin-bar.css b/src/wp-includes/css/admin-bar.css
index c4e8ba3afa..80650ed530 100644
--- a/src/wp-includes/css/admin-bar.css
+++ b/src/wp-includes/css/admin-bar.css
@@ -97,6 +97,9 @@ html:lang(he-il) .rtl #wpadminbar * {
 	min-width: 600px; /* match the min-width of the body in wp-admin/css/common.css */
 	z-index: 99999;
 	background: #1d2327;
+
+	/* Only visible in Windows High Contrast mode */
+	outline: 1px solid transparent;
 }
 
 #wpadminbar .ab-sub-wrapper,