diff --git a/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/editorui/editorui.css b/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/editorui/editorui.css
index 24b6d9e4809..b8326cfb494 100644
--- a/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/editorui/editorui.css
+++ b/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/editorui/editorui.css
@@ -9,6 +9,10 @@
 @import "../../../mixins/_focus.css";
 @import "../../mixins/_button.css";
 
+:root {
+	--ck-color-editable-blur-selection: hsl(0, 0%, 85%);
+}
+
 .ck.ck-editor__editable:not(.ck-editor__nested-editable) {
 	@mixin ck-rounded-corners;
 
@@ -40,6 +44,11 @@
 	& > *:last-child {
 		margin-bottom: var(--ck-spacing-large);
 	}
+
+	/* https://github.com/ckeditor/ckeditor5/issues/6517 */
+	&.ck-blurred ::selection {
+		background: var(--ck-color-editable-blur-selection);
+	}
 }
 
 /* https://github.com/ckeditor/ckeditor5-theme-lark/issues/111 */
diff --git a/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/formheader/formheader.css b/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/formheader/formheader.css
deleted file mode 100644
index 11363fe7e05..00000000000
--- a/packages/ckeditor5-theme-lark/theme/ckeditor5-ui/components/formheader/formheader.css
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
- * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
- */
-
-:root {
-	--ck-table-form-header-height: 38px;
-}
-
-.ck.ck-form__header {
-	padding: var(--ck-spacing-small) var(--ck-spacing-large);
-	height: var(--ck-table-form-header-height);
-	line-height: var(--ck-table-form-header-height);
-	border-bottom: 1px solid var(--ck-color-base-border);
-
-	& .ck-form__header__label {
-		font-weight: bold;
-	}
-}