wp_custom_login_child_theme.css

body.login {}
body.login div#login {}
body.login div#login h1 {}
body.login div#login h1 a {}
body.login div#login form#loginform {}
body.login div#login form#loginform p {}
body.login div#login form#loginform p label {}
body.login div#login form#loginform input {}
body.login div#login form#loginform input#user_login {}
body.login div#login form#loginform input#user_pass {}
body.login div#login form#loginform p.forgetmenot {}
body.login div#login form#loginform p.forgetmenot input#rememberme {}
body.login div#login form#loginform p.submit {}
body.login div#login form#loginform p.submit input#wp-submit {}
body.login div#login p#nav {}
body.login div#login p#nav a {}
body.login div#login p#backtoblog {}
body.login div#login p#backtoblog a {}

wp_custom_login_child_theme.php

<?php
/* Insert in funtcions.php for child themes */
/* Customize login */
function my_login_stylesheet() {
    wp_enqueue_style( 'custom-login', get_stylesheet_directory_uri() . '/css/style-login.css' );
}
add_action( 'login_enqueue_scripts', 'my_login_stylesheet' );

function my_login_logo_url($url) {
	return home_url();
}
add_filter( 'login_headerurl', 'my_login_logo_url' );

?>