Adding a Child Theme to Divi style.css and functions.php. Add a child folder in /wp-content/themes/..

functions.php

<?php
add_action( 'wp_enqueue_scripts', 'my_enqueue_assets' );
function my_enqueue_assets() {
    wp_enqueue_style( 'parent-style', get_template_directory_uri().'/style.css' );
}

style.css

/*
Theme Name: My Divi Child Theme
Theme URI: http://mydomain.com/
Version: 1.0
Description: A customized version of Divi which adds a number of tiny features I need.
Author: Your Name
Author URI: http://www.yourwebsite.com
Template: Divi
*/