Reply To: ''Adding a menu toggle button on small screens'' in WordPress

[admin]

Please also pass the 'container' => 'false' parameter and it should work – e.g.:

<?php wp_nav_menu( array( 'theme_location' => 'primary', 'container' => 'false', 'menu_id' => 'main-menu', 'menu_class' => 'sm sm-mint' ) ); ?>