Hi @Vlad_Posibl! There was a recent post in the Community Show & Tell category that could potentially help with this issue. In general, though, class selectors are not expected to be stable and we recommend using the _retool-componentName selector whenever possible.
It sounds like you want more granular control, though, so I understand why you'd want to use the raw class name selectors. I did some testing on a few different browsers and the class names never changed. I assume you're viewing the app as a user and not an editor?
The only thing that comes to mind is that an extension is mutating the class names but that wouldn't persist through a refresh, so I'm at a bit of a loss.