Hello,
We have fixed the major issue that you get after the update (we edited php and CSS files of your child theme and also mu-plugins/index.php because your developer added a few theme functions there). You have a lot of changes in your child theme. If some CSS styles are still missing you will need to check the code that you added before and make sure that all the classes are correct in the previous code because we change the structure a little bit and I’m not sure if all the styles are correct on your site.
Regards