diff --git a/packages/block-library/src/image/index.php b/packages/block-library/src/image/index.php
index 996dbe6abf60d..e62983b809a4c 100644
--- a/packages/block-library/src/image/index.php
+++ b/packages/block-library/src/image/index.php
@@ -252,10 +252,22 @@ function block_core_image_render_lightbox( $block_content, $block ) {
 	$q->set_attribute( 'data-wp-style--object-fit', 'selectors.core.image.lightboxObjectFit' );
 	$enlarged_image_content = $q->get_updated_html();
 
-	$background_color = esc_attr( wp_get_global_styles( array( 'color', 'background' ) ) );
+	// If the current theme does NOT have a `theme.json`, or the colors are not defined,
+	// we need to set the background color & close button color to some default values
+	// because we can't get them from the Global Styles.
+	$background_color   = '#fff';
+	$close_button_color = '#000';
+	if ( wp_theme_has_theme_json() ) {
+		$global_styles_color = wp_get_global_styles( array( 'color' ) );
+		if ( ! empty( $global_styles_color['background'] ) ) {
+			$background_color = esc_attr( $global_styles_color['background'] );
+		}
+		if ( ! empty( $global_styles_color['text'] ) ) {
+			$close_button_color = esc_attr( $global_styles_color['text'] );
+		}
+	}
 
 	$close_button_icon  = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="15" height="15" aria-hidden="true" focusable="false"><path d="M13 11.8l6.1-6.3-1-1-6.1 6.2-6.1-6.2-1 1 6.1 6.3-6.5 6.7 1 1 6.5-6.6 6.5 6.6 1-1z"></path></svg>';
-	$close_button_color = esc_attr( wp_get_global_styles( array( 'color', 'text' ) ) );
 	$dialog_label       = $alt_attribute ? esc_attr( $alt_attribute ) : esc_attr__( 'Image' );
 	$close_button_label = esc_attr__( 'Close' );
 
diff --git a/packages/block-library/src/image/style.scss b/packages/block-library/src/image/style.scss
index c7eec224f6587..707b33058a226 100644
--- a/packages/block-library/src/image/style.scss
+++ b/packages/block-library/src/image/style.scss
@@ -169,6 +169,13 @@
 			outline: 5px auto -webkit-focus-ring-color;
 			outline-offset: 5px;
 		}
+
+		&:hover,
+		&:focus,
+		&:not(:hover):not(:active):not(.has-background) {
+			background: none;
+			border: none;
+		}
 	}
 }
 
@@ -191,6 +198,13 @@
 		padding: 0;
 		cursor: pointer;
 		z-index: 5000000;
+
+		&:hover,
+		&:focus,
+		&:not(:hover):not(:active):not(.has-background) {
+			background: none;
+			border: none;
+		}
 	}
 
 	.lightbox-image-container {