How to hide tags on published posts?

I don’t see the tags, it looks like your CSS is working fine. You should disable any cache plugins while you are making changes and then reactivate them, or else flush the cache so it refreshes. Then your changes will show up right away.

One other thing you should be aware of: You shouldn’t be making changes to the theme files (like the stylesheet) directly. If the theme gets updated because of feature enhancements, bug fixes, or security patches, or if the theme has to be updated because of a change to the WordPress core, then your changes will be lost. Instead, either create a child theme or use a CSS plugin like Jetpack or Custom CSS Manager.