Hi Hynek
The child theme is not working properly. If you want to modify the theme files, before making any changes in css code or in any functionality, please keep backup of original theme so you can use it in your next project. You can make changes in any part of the themes as per your requirement.
The MedPlus WordPress theme is GPL-licensed which means you can use them as many websites as you like for commercial or private purposes.
If you have any questions regarding MedPlus WordPress themes, you can contact us at any stage of your website development. Our support team is always ready to help you with any problems of customization.
Regards
Grace Themes