CSS style button For WP Login Function in page template

You just need to add a function to style the login form:

function my_login_css() {

?>
 <style type="text/css">
 #wp-submit {
  border-color: #777;
  background: #999;
  box-shadow: none;
  text-shadow: none; 
  border-radius: 0px;
 }
 #wp-submit:hover {background: #ccc}

</style>
 <?php
}
add_action('login_enqueue_scripts', 'my_login_css');

When using a theme, like Avada, it’s best to add these custom functions to a child theme. More information, specific to Avada.