document replaced/deleted theme variables per 2025.8

[Mariusthvdb]

Describe the improvement

this is a generic request, not perse per a specific page:
case: as of 2025.8 we've not only seen the introduction of the color-palettes, which is a very serious undertaking ;-0
we managed to cope with that in our themes, and various discussion in the community tackle that.

Besides implementing those new variables, there somehow seem to also be several lost theme variables. We notice because our frontend Inspector mentions undefined css selectors, in various syntaxes.

I take it the core HA frontend code wont suffer from that, but custom cards that rely on the known variables apparently do.

So please consider this request to list the changes in theme variables, especially the ones that are no longer used, and deleted from the code completely.

A dev blog would probably suffice, to alerts custom card authors to adjust their contributions to the project

I get that the pov from the team is those theme variables are not officially supported, so are not documented either. That is why I dont ask for them to be mentioned in the Documentation for the Frontend (I would not protest/object though...)

As a Courtney to the growing user-base, and considering the vast number of questions in the community it would be great to see those changes, and be able to replace/strike them

Anything else?

No response