You can use Divi’s built-in media queries to add custom CSS targeted for each device. I suggest using the Theme Customizer for this. It allows you to add your Custom CSS to your theme and see the results for each device in real time all in one place.
Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.