In editor-style.css how can I change background color of title field?

Editor styles only apply to the TinyMCE content area. If you'd like to apply styles to other elements on the edit page, you'll need to enqueue a separate stylesheet.

For example, add this to the theme's functions.php:

function wpse250011_admin_styles( $hook ) {
    // Bail if we're not on the post.php admin page
    if ( 'post.php' !== $hook ) {
        return;
    }

    // Ensure we're looking at a post or page
    $post_type = get_post_type();
    if ( ! $post_type || ! in_array( $post_type, [ 'post', 'page' ] ) ) {
        return;
    }

    wp_enqueue_style( 'admin-edit-post-styles', get_template_directory_uri() . '/admin-edit-post.css' );
}
add_action( 'admin_enqueue_scripts', 'wpse250011_admin_styles' );

Add the styles for the admin components, such as the title field to a separate file: /your-theme/admin-edit-post.css

#titlediv #title {
     background-color: #ffffcc;
}