Add css code in admin_enqueue_scripts
If you’re using the admin_enqueue_scripts hook, use wp_enqueue_script() to enqueue a CSS file with the styles you want to apply. If you want to output a <style></style> element use the admin_head hook to output it between the <head></head> tags: function custom_css_stuff() { ?> <style type=”text/css”> body { color: red; } </style> <?php } add_action( ‘admin_head’, … Read more