diff --git a/packages/edit-site/src/components/global-styles/style.scss b/packages/edit-site/src/components/global-styles/style.scss
index 07f3c7a95c800d..3560ef139fa3fe 100644
--- a/packages/edit-site/src/components/global-styles/style.scss
+++ b/packages/edit-site/src/components/global-styles/style.scss
@@ -85,23 +85,35 @@
 
 .edit-site-global-styles-variations_item {
 	box-sizing: border-box;
+	// To round the outline in Windows 10 high contrast mode.
+	border-radius: $radius-block-ui;
 
 	.edit-site-global-styles-variations_item-preview {
 		padding: $border-width * 2;
 		border-radius: $radius-block-ui;
-		border: $gray-200 $border-width solid;
+		box-shadow: 0 0 0 $border-width $gray-200;
+		// Shown in Windows 10 high contrast mode.
+		outline: 1px solid transparent;
 	}
 
 	&.is-active .edit-site-global-styles-variations_item-preview {
-		border: $gray-900 $border-width solid;
+		box-shadow: 0 0 0 $border-width $gray-900;
+		// Shown in Windows 10 high contrast mode.
+		outline-width: 3px;
 	}
 
 	&:hover .edit-site-global-styles-variations_item-preview {
-		border: var(--wp-admin-theme-color) $border-width solid;
+		box-shadow: 0 0 0 $border-width var(--wp-admin-theme-color);
 	}
 
 	&:focus .edit-site-global-styles-variations_item-preview {
-		border: var(--wp-admin-theme-color) var(--wp-admin-border-width-focus) solid;
+		box-shadow: 0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color);
+	}
+
+	&:focus-visible {
+		// Shown in Windows 10 high contrast mode.
+		outline: 3px solid transparent;
+		outline-offset: 0;
 	}
 }
 
diff --git a/packages/edit-site/src/components/sidebar-navigation-screen/style.scss b/packages/edit-site/src/components/sidebar-navigation-screen/style.scss
index 4efdbad33a5430..f658083cc19f4e 100644
--- a/packages/edit-site/src/components/sidebar-navigation-screen/style.scss
+++ b/packages/edit-site/src/components/sidebar-navigation-screen/style.scss
@@ -90,17 +90,16 @@
 	}
 
 	.edit-site-global-styles-variations_item-preview {
-		border: $gray-900 $border-width solid;
+		box-shadow: 0 0 0 $border-width $gray-900;
 	}
 	.edit-site-global-styles-variations_item.is-active .edit-site-global-styles-variations_item-preview {
-		border: $gray-100 $border-width solid;
+		box-shadow: 0 0 0 $border-width $gray-100;
 	}
 	.edit-site-global-styles-variations_item:hover .edit-site-global-styles-variations_item-preview {
-		border: var(--wp-admin-theme-color) $border-width solid;
+		box-shadow: 0 0 0 $border-width var(--wp-admin-theme-color);
 	}
-
 	.edit-site-global-styles-variations_item:focus .edit-site-global-styles-variations_item-preview {
-		border: var(--wp-admin-theme-color) var(--wp-admin-border-width-focus) solid;
+		box-shadow: 0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color);
 	}
 }