Help! CSS for default Login Page

I like the default login page. However, I would like to center the login form. How can I inject css to center the login form vertically? TIA

I tried adding the following snippet to both the code snippet and fluentsnippet ...didn't work:

add_action('fluent_community/portal_head', function() {

?>
\

/ Add your custom CSS here /

.fcom_user_onboard {

max-width: 600px;

margin: 0 auto;

padding: 300px 40px 20px;

}
\

\<?php

});