How to make Gutenberg wider

Editing a page in the block editor has an unpleasant feature – strip with the page mock is too narrow – 610px only, and this cause inconvenience with big number of columns. Page mock is narrow, but there is too much empty space around.

All that you should do – just to add one rule to the admin styles. For this, add the following code to the `functions.php` file of your theme:

/**
 * Enqueue admin scripts.
 */
function my_admin_enqueue_scripts() {
	wp_enqueue_style(
		'admin',
		get_stylesheet_directory_uri() . '/css/admin.css',
		[],
		'1.0'
	);
}

add_action( 'admin_enqueue_scripts', 'my_admin_enqueue_scripts' );

Then, in the css subfolder of your theme create a file named admin.css with the following content:

.wp-admin .wp-block {
	 max-width: 100%;
}