Function — Customize Wordpress logo on wp login page - martindubenet/Wordpress GitHub Wiki
This function dates from 2010, so it may not work on latest Wordpress.
The following scripts requires a 280 x 140 pixels image to be located in this location
/img/wp-admin/login-logo.pngbased on your theme's root.
/**
* Customize replace WordPress's logo shown in `wp-longin.php`
*/
function custom_wplogin_style() {
echo '<style type="text/css">
.login #nav a {color:#00458A!important;} .login #nav a:hover {color:#005EBD!important;}
h1 a { display:block; margin:0 auto; width:280px; height:140px; background-image: url(' . get_template_directory_uri() . '/img/wp-admin/login-logo.png)!important; background-position: center center; }
input.button-primary, button.button-primary, a.button-primary {border-color:#333; background:#00458A;}
input.button-primary:hover, button.button-primary:hover, a.button-primary:hover {border-color:#333; background:#005EBD;}
</style>';
}
add_action('login_head', 'custom_wplogin_style');