diff --git a/packages/block-editor/src/components/block-toolbar/style.scss b/packages/block-editor/src/components/block-toolbar/style.scss
index 0c2ed94c01e3f0..98538d5d1d053d 100644
--- a/packages/block-editor/src/components/block-toolbar/style.scss
+++ b/packages/block-editor/src/components/block-toolbar/style.scss
@@ -70,7 +70,7 @@
 	// Raise the specificity.
 	&.components-accessible-toolbar {
 		border: none;
-		border-bottom: $border-width solid $gray-200;
+		box-shadow: 0 $border-width 0 0 rgba($color: #000, $alpha: 0.133); // 0.133 = $gray-200 but with alpha.
 		border-radius: 0;
 	}
 
diff --git a/packages/editor/src/components/header/style.scss b/packages/editor/src/components/header/style.scss
index 99c9cc70e166e4..8712121fff3ea6 100644
--- a/packages/editor/src/components/header/style.scss
+++ b/packages/editor/src/components/header/style.scss
@@ -243,7 +243,7 @@
 		width: 100%;
 
 		@include break-medium {
-			border-bottom: 1px solid #e0e0e0;
+			box-shadow: 0 $border-width 0 0 rgba($color: #000, $alpha: 0.133); // 0.133 = $gray-200 but with alpha.
 			position: absolute;
 		}