Hi,
We don’t have any similar problem in other installations. I checked with the major plugins disabled and it worked fine so it’s a problem in of your plugins.
Your hosting is incorrect this has nothing to with css.
Try to disable everything except SwiftFramework and Woocommerce(the necessary plugins to start the store), clear the cache and try again. It worked for me, after that you should activate the plugins one by one to confirm where the problem is.
You should also check for your server error log files so we can find any further information.
-Rui