Child Theme, Theme Installation Guide, CSS broken

Hello James,
Thanks for using our theme SuperMagPro. Are you currently working on your site? Did you changed some code on theme ? If so let us know, there is no any bug on theme because we set up a demo and it is working fine. Please make sure you installed the whole package of theme, no missing any files.
If you have any problem more, please let us know.
Best Regards,
Acme Supports

Yes definitely our theme is child theme friendly, you can even override inner file of themes not only templates files.
Your child theme css is blank, please write following css in the child theme style.css:

/*
 Theme Name:   SuperMagPro Child
 Theme URI:    http://www.acmethemes.com/themes/supermagpro/
 Description:  SuperMagPro Child Theme
 Author:       Acme Themes
 Author URI:   http://www.acmethemes.com/
 Template:     supermagpro
 Version:      1.0.0
 License:      GNU General Public License v2 or later
 License URI:  http://www.gnu.org/licenses/gpl-2.0.html
 Tags:         orange, brown, yellow etc
 Text Domain:  supermagpro-child
*/

Again in functions.php file please write following codes:

<?php
function suprmagpro_child_enqueue_styles() {

    $parent_style = 'parent-style';

    wp_enqueue_style( $parent_style, get_template_directory_uri() . '/style.css' );
    wp_enqueue_style( 'child-style',
        get_stylesheet_directory_uri() . '/style.css',
        array( $parent_style )
    );
}
add_action( 'wp_enqueue_scripts', 'suprmagpro_child_enqueue_styles' );
?>

Here is further docs https://codex.wordpress.org/Child_Themes.

this should fix the problems.
if you again have any problem please feel free to ask.

Best Regards,
AcmeThemes