Custom logo on WP login screen

functions.php

function ak_custom_login_logo() {
	wp_enqueue_style( 'ak_custom_login_logo', get_stylesheet_directory_uri() . '/login.css' );
}
add_action('login_head', 'ak_smj_custom_login_logo');

login.css

#login h1 a { 
	background-image: url("http://sitename.com/wp-content/themes/themename/images/logo-wp.png")!important; 
	background-size: 280px 115px; 
	height: 100px; 
}