WordPress: Add custom CSS to admin pages and login page

You can add custom CSS to all admin pages by adding this function to functions.php (located in your theme’s subdirectory in wp-content/themes).

function admin_css() { ?>
   <style type="text/css">
      h1 { color: red; }
   </style>
<?php }
add_action('admin_head', 'admin_css');

To add custom CSS to the WordPress login page, add the following to functions.php. This CSS example will override the WordPress logo.

function login_css() { ?>
   <style type="text/css">
      .login h1 a { background-image: url(/img/logo.png) !important; }
   </style>
<?php }
add_action( 'login_enqueue_scripts', 'login_css' );

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