Cheatsheet for customising the WordPress Login page

functions.php

<?php
// Cheatsheet for customising the WordPress Login page

function my_custom_login() {
	echo '<link rel="stylesheet" type="text/css" href="' . get_bloginfo('stylesheet_directory') . '/login/ENTER_URL.css" />';
}
add_action('login_head', 'my_custom_login');

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

function my_login_logo_url_title() {
    return 'Your Site Name and Info';
}
add_filter( 'login_headertitle', 'my_login_logo_url_title' );

function login_error_override() {
    return 'Incorrect login details.';
}
add_filter('login_errors', 'login_error_override');

function admin_login_redirect( $redirect_to, $request, $user ) {
    global $user;
    if( isset( $user->roles ) && is_array( $user->roles ) ) {
        if( in_array( "administrator", $user->roles ) ) {
            return $redirect_to;
        } else {
            return home_url();
        }
    } else {
        return $redirect_to;
    }
}
add_filter("login_redirect", "admin_login_redirect", 10, 3);

style.css

html {
    height: 100%;
    background: #ffffff url('ENTER_URL') no-repeat center top fixed;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
}

body {
    background: none;
    min-width: 0;
    padding-top: 8%;
    color: #FFF;
}

#login {
    background-color: #ffffff;
    border: 0 solid #ffffff;
    -webkit-border-radius: 11px;
    border-radius: 11px;
    -moz-background-clip: padding;
    -webkit-background-clip: padding-box;
    background-clip: padding-box;
    background-color: rgba(255,255,255,0.85);
    padding: 15px 20px;
}

.login #login_error, 
.login .message {
    background-color: #444;
}    

.login h1 a {
    background-image: url('ENTER_URL');
    background-size:auto;
    width: 300px;
    height: 132px;
}