Update comment

packages/edit-site/src/components/block-editor/index.js

@@ -70,7 +70,9 @@ export default function BlockEditor( { setIsInserterOpen } ) {
 	const contentRef = useRef();
 
 	useMouseMoveTypingReset( ref );
-	// Ideally this should be moved to the place where the styles are applied (iframe)
+	// This updates the host document styles.
+	// It is necessary to make sure the preset CSS Custom Properties
+	// are in scope for the sidebar UI controls that use them.
 	const editorStylesRef = useEditorStyles( settings.styles );
 
 	// Allow scrolling "through" popovers over the canvas. This is only called