diff --git a/gutenberg.php b/gutenberg.php
index 37215edb4a89d7..c096463f53bf13 100644
--- a/gutenberg.php
+++ b/gutenberg.php
@@ -28,6 +28,25 @@
 function the_gutenberg_project() {
 	global $post_type_object;
 	?>
+	<noscript>
+		<div class="error" style="position:absolute;top:32px;z-index:40"><p>
+		<?php
+			// Using Gutenberg as Plugin
+			if ( is_plugin_active( 'gutenberg/gutenberg.php' ) ) {
+				$current_url = esc_url( add_query_arg( 'classic-editor', true, $_SERVER['REQUEST_URI'] ) );
+				printf(
+					__( 'The Block Editor requires JavaScript. You can use the <a href="%s">Classic Editor</a>.', 'gutenberg' ),
+					$current_url
+				) ;
+			} else { // Using Gutenberg in Core
+				printf(
+					__( 'The Block Editor requires JavaScript. Please try the <a href="%s">Classic Editor plugin</a>.', 'gutenberg' ),
+					'https://wordpress.org/plugins/classic-editor/'
+				) ;
+			}
+		?>
+		</p></div>
+	</noscript>
 	<div class="block-editor gutenberg">
 		<h1 class="screen-reader-text"><?php echo esc_html( $post_type_object->labels->edit_item ); ?></h1>
 		<div id="editor" class="block-editor__container gutenberg__editor"></div>
@@ -123,7 +142,7 @@ function is_gutenberg_page() {
  */
 function gutenberg_wordpress_version_notice() {
 	echo '<div class="error"><p>';
-	echo __( 'Gutenberg requires WordPress 4.9.8 or later to function properly. Please upgrade WordPress before activating Gutenberg.', 'gutenberg' );
+	_e( 'Gutenberg requires WordPress 4.9.8 or later to function properly. Please upgrade WordPress before activating Gutenberg.', 'gutenberg' );
 	echo '</p></div>';
 
 	deactivate_plugins( array( 'gutenberg/gutenberg.php' ) );
@@ -136,7 +155,7 @@ function gutenberg_wordpress_version_notice() {
  */
 function gutenberg_build_files_notice() {
 	echo '<div class="error"><p>';
-	echo __( 'Gutenberg development mode requires files to be built. Run <code>npm install</code> to install dependencies, <code>npm run build</code> to build the files or <code>npm run dev</code> to build the files and watch for changes. Read the <a href="https://github.com/WordPress/gutenberg/blob/master/CONTRIBUTING.md">contributing</a> file for more information.', 'gutenberg' );
+	_e( 'Gutenberg development mode requires files to be built. Run <code>npm install</code> to install dependencies, <code>npm run build</code> to build the files or <code>npm run dev</code> to build the files and watch for changes. Read the <a href="https://github.com/WordPress/gutenberg/blob/master/CONTRIBUTING.md">contributing</a> file for more information.', 'gutenberg' );
 	echo '</p></div>';
 }
 
diff --git a/packages/edit-post/src/components/fullscreen-mode/style.scss b/packages/edit-post/src/components/fullscreen-mode/style.scss
index 4afd36c4b8eb6f..b1ed94ff7452f2 100644
--- a/packages/edit-post/src/components/fullscreen-mode/style.scss
+++ b/packages/edit-post/src/components/fullscreen-mode/style.scss
@@ -1,4 +1,4 @@
-body.is-fullscreen-mode {
+body.js.is-fullscreen-mode {
 	// Reset the html.wp-topbar padding
 	// Because this uses negative margins, we have to compensate for the height.
 	margin-top: -$admin-bar-height-big;