Updating Style From WP Options Setting Page

I think you have to solve this with jQuery. If checked -> addClass, if not -> removeClass.

Here’s how to enqueue your JS file:

add_action('admin_menu', 'fwds_plugin_settings');

function fwds_plugin_settings() {
    $hook = add_menu_page(
        'Price Display', 
        'Price Display', 
        'add_users', 
        'fwds_settings', 
        'fwds_display_settings'
    );
    add_action( "admin_print_scripts-$hook", 'fwds_print_scripts' );
}
function fwds_print_scripts()
{
    wp_register_script( 
         'my-fx' 
        , plugin_dir_url( __FILE__ ) . '/my-fx.js'
        , array( 'jquery' ) // Dependencies
    );

    wp_enqueue_script( 'my-fx' );
}

And my-fx.js:

jQuery(document).ready(function($) 
{   
    alert('my page');
});