Add custom logo for WordPress login screen. Add it to the functions.php file.

wp_customloginlogo

/******* Customize Login Logo ******/
function my_custom_login_logo() {
    echo '<style type="text/css">
        h1 a { background-image:url('.get_bloginfo('stylesheet_directory').'/images/login_logo.png) !important; background-size: 287px 66px !important; height: 66px !important; width: 287px !important; margin-left: 20px !important; }
    </style>';
}
add_action('login_head', 'my_custom_login_logo');