Enqueue style.css

<?php

/**
 * theme functions and definitions
 *
 * @link https://developer.wordpress.org/themes/basics/theme-functions/
 *
 * @package theme
 */


/**
* Enqueue scripts and styles.
*/
function theme_scripts() {
    wp_enqueue_style( 'theme-style', get_stylesheet_uri(), array(), 0 );

}
add_action( 'wp_enqueue_scripts', 'theme_scripts' );