How to buy gift certificates online?

Question

PHP

It is necessary to implement something similar: example

What should be the sequence of actions, if you were doing this task?

PS Plugins and woocomerce are not suitable! Please don't write about it.

Answer 1

Try like this

wp_enqueue_style('style', get_template_directory_uri() . '/style.css', array());

Answer 2

At least here:
add_action('wp_enqueue_scripts','default_styles');