/**
 * WP Tutorials : Customise WooCommerce Shipping Rates Layout, CWSRL
 *
 * https://wp-tutorials.tech/refine-wordpress/woocommerce-shipping-methods-as-a-dropdown-list/
 */

.woocommerce ul#shipping_method {
   display: none;
}

/* Add your custom drop-down list CSS here */
/* ... */